This very old book by Farnell on Greek Conditional and Relative sentences will be useful to those like me who find the treatment in general textbooks is too brief.
http://babel.hathitrust.org/cgi/pt?id=uc2.ark:/13960/t3805830n;view=1up;seq=5
There is a similar free offline app for the iPhone/iPad – it’s called Logeion, created by the University of Chicago Classics Department.
You can use the app to search many of the reference works in the Perseus Classical collection in both Latin and Greek, provided you install the Greek keyboard layout on your device.
Ancient Greek Grammar: 103 lessons on YouTube by Nicholas Gresens, Ph.D.
Two resources of Ancient Greek and Latin texts in French:
Hodoi elekronikai du texte à l’hypertexte
http://mercure.fltr.ucl.ac.be/Hodoi/concordances/intro.htm
For Ancient Greek Texts, the Home Page lists authors whose texts are in the collection, and its coverage is similar to Perseus’s.
With the individual work for each author, there is a separate page for
- a list of word forms in the work
- an inverse list of word forms, in alphabetical order by LAST letter of the word
e.g., for δ
21 δ
1 οὐδ
-
frequencies of words
-
appearance of the words in other texts
-
the context of the words in the current text
e.g., for Plutarch’s “Sylla”:
Chapitre [33] γέ τοι βουλόμενος οἰκειώσασθαι τὸν Μάγνον, -
the context of the words in the current text, but by last letter
-
a link to the Bibliotheca Classica Selecta (BCS)
For many but not all of the works there is a French translation. Except for the translations in French, I would guess you could make use of this site even without a knowledge of French.
Their site for Latin texts is here:
http://agoraclass.fltr.ucl.ac.be/concordances/intro.htm
There are now editions similar to Steadman’s, but not digital, and not, as far as I can tell, free in any way.
The authors of one set of such words are Evan Hayes and Stephen Nimis, and the author of another set is C. T. Hadavas. All three are academics, and you can probably find their works at your favorite bookseller.
This link is dead due to the merger of JACT and CA. I could not find the link at CA (though I did not try very hard 
)
_From Moderator:
substituted link to archived page.
https://web.archive.org/web/20091224041815/http://www.jact.org/publications/goodtext/goodtextguide.php_
This is a list of works originally composed in Latin for which a Greek translation exists on the Internet (mostly on Google Books). Obviously, the percentage of Greek works translated into Latin is much higher.
More or less contemporary translations
Res Gestae Divi Augusti
http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Augustus/Res_Gestae/home.html
Eutropi Breviarium ab urbe condita translated by Paeanius sophist
https://books.google.com/books?id=n-0JAAAAIAAJ&pg=PA8#v=twopage&q&f=false
De viris illustribus St. Jerome
https://archive.org/stream/patrologiaecurs01goog#page/n322/mode/2up
SANCTI GREGORII PAPAE DIALOGORUM LIBRI IV
https://archive.org/stream/patrologiaecurs06goog#page/n77/mode/2up I, III, IV
https://archive.org/stream/patrologiaecurs115unkngoog#page/n65/mode/2up II
Byzantine translations
Translation by Maximus Planudes
Heroides Ovid
https://books.google.com/books?id=4JWTI37spGoC&pg=PA161#v=onepage&q&f=false
Metamorphoses Ovid
https://books.google.com/books?id=ZktcAAAAcAAJ&pg=PR22#v=onepage&q&f=false
Epistulae XX et XXI
https://books.google.com/books?id=CZolAAAAMAAJ&pg=PA157#v=onepage&q&f=false
De consolatione philosophiae Boethius
https://books.google.com/books?id=MPlRAAAAcAAJ&pg=PA1#v=onepage&q&f=false
Carmina - Boethius
https://books.google.com/books?id=suhQAAAAcAAJ
De bello gallico
https://books.google.com/books?id=5xE9AAAAcAAJ&pg=PA1#v=onepage&q&f=false
Disticha Catonis
https://books.google.com/books?id=unATAAAAQAAJ&pg=PT16#v=onepage&q&f=false
https://books.google.com/books/about/Maximus_Planudes_Disticha_Catonis_in_Gra.html?id=xjJ5mwEACAAJ
De Trinitate
http://www.bl.uk/manuscripts/FullDisplay.aspx?ref=Harley_MS_5687
M.T. Ciceronis Cato Maior, Somnium Scipionis, Laelius et Paradoxa
https://books.google.com/books?id=9CBBAAAAMAAJ&pg=PA1#v=onepage&q&f=false
Gaza, Planudes,Petau, Turnèbe
Other translations
M. Tullii Ciceronis Paradoxa Graece versa et explicata ab Joanne Morisoto
https://books.google.com/books?id=-WRjAAAAcAAJ
Greek colloquies
Jesuits
Officium corporis Christi
https://books.google.com/books?id=o2c8AAAAcAAJ&pg=PA1#v=twopage&q&f=false
Catechismus gr., lat. et gallice
By saint Petrus (Canisius)
https://books.google.com/books?id=ZYk9AAAAcAAJ&pg=PR4-IA2#v=twopage&q&f=false
De Imitatione Christi Libri quatuor
By Thomas a Kempis, Mayr
https://books.google.com/books?id=uNjR4uKSUTIC&pg=PA11#v=onepage&q&f=false
https://books.google.com/books?id=1f8k4BMLZ68C&&pg=PP7#v=onepage&q&f=false
Vita B. Ignati Societatis Iesu Fundatoris
https://books.google.com/books?id=0cUWAAAAQAAJ&pg=PA1#v=twopage&q&f=false
Litaniae De Venerabili Sacramento Eucharistiae. Item Sequentia S. Thomae
https://books.google.com/books?id=hm1FAAAAcAAJ&pg=PT1#v=twopage&q&f=false
Officium Beatae Mariae Virginis Latinograecum: Ad Latinum editionem Romae …
By Georg Mayr
https://books.google.com/books?id=iTVFAAAAcAAJ&pg=RA2-PR5#v=twopage&q&f=false
Fascicvlvs Sacrarvm Litaniarvm
https://books.google.com/books?id=b9c8AAAAcAAJ&pg=PA5#v=twopage&q&f=false
Quattuor dialogi ex Progymnasmatis Jacobi Pontani, Societatis Jesu, Graece
redditi
https://books.google.com/books?id=ylcP8CUhjaUC&pg=PA29#v=onepage&q&f=false
Greek Dialogues, Hymns, Prayers, the Catechism and Dionysius Cato from Jacob Gretser S. J. Rudementa Linguae Graecae, edited by Fergus Walsh
https://archive.org/details/Gretser-four-greek-dialogues
P. Stanislav Rapal SJ
GYMNASION GRAECO-LATINUM: Piarum precum & Sacrorum Hymnorum, tam in publicis quam privatis devotionibus A studiosa Juventute Collegii Vratislaviensis Societatis Jesu frequentari solitum. In ejusdem Studiosae Juventutis ac Omnium FIL[H]ELLENON Gratiam & usum concinnatum
https://books.google.com/books?id=Y2VkAAAAcAAJ
Works by Comenius
Orbis pictus
https://archive.org/details/njerickson07_gmail_3.0
Vestibulum
https://books.google.com/books?id=ZCBGAAAAcAAJ&pg=PP27#v=onepage&q&f=false
Janua Linguarum Reserata
https://drive.google.com/folderview?id=0BwyQgrJPS6GBXzhmSEFYRWR0ekE&usp=sharing
Scientiarum Elementa Gr. et Lat. sibi quædam ex J. C. Opere notissimo
https://books.google.com/books?id=jRZgAAAAcAAJ&pg=PP1#v=onepage&q&f=false
On the subject
De Latine scriptis quæ Græci veteres in linguam, suam transtulerunt
Carolus Fridericus Weber
De romanorum juris publici sacrique vocabulis sollemnibus in graecum sermonem conversis
David Magie
ΕΛΛΗΝΙΚΑ ΛΕΙΤΟΥΡΓΙΚΑ ΚΕΙΜΕΝΑ ΤΗΣ ΟΡΘΟΔΟΞΗΣ ΕΚΚΛΗΣΙΑΣ
Complete (?) books of the Byzantine liturgy, enormous, organically grown, and never butchered like the Roman 
I have added a pdf with the section on Book 1 of Xenophon’s Anabasis
from
Expeditio Cyri / Xenophon; by J.F. MacMichael.
It is crude ( I used a camera not a scanner) but nonetheless usable.
You will find it here:
http://kart-hadasht.co.uk/anc/greeklang/
(scroll down to the section headed Commentaries)
The link brings up an Error 404, Object Not Found message.
Ouch! 
And not the first time I made that mistake. However this gives me a chance to mention that now also downloadable from the same page (http://kart-hadasht.co.uk/anc/greeklang/) is Commentary on The Oeconomicus by A.H.N. Sewell which is a proper scan. Sewell did include the Greek text along with his commentary but suspect most will go to Perseus for that.
Thanks for pointing out my error I apologies to all who followed the link in vain.
Just FYI, that’s known as the “lunate” sigma, meaning it’s shaped like a half-moon. The OCT actually published some texts using it (Diggle’s Euripides, for one), but that was also the time when they switched to prefaces in English. And the prices have gone through the roof as the bindings have gone to hell. I can’t believe OUP thinks they deserve our money any more. (I guess this post went kinda sideways…)
State of the art free software project as of 2018: alpheios Firefox Browser addon
-featurecomplete
a “mouse over look up” included, on key (doubleclick)
-waterproof a syntaxmachine for words and even sentences
-linked to off(?)- and online Greek main web dictionaries?
What do you neet more?
-Understanding the code of a grammar machine these days, might be the most proper way of being occupied with it - for some to note: You could start with it now.
just for completeness I used:
Up to now
-for simple grammar I use https://de.wikipedia.org/wiki/Altgriechische_Flexion, which is really other than complete,
-for translation beneath reading I used for bible koine: https://www.biblegateway.com/passage/?search=+ΚΑΤΑ+ΜΑΤΘΑΙΟΝ+5%3A21-&version=SBLGNT;LUTH1545
-and for dictionary I mark, copy a word (with the finger) on my android smart phone, switch the browser window and paste it, being online it to lexiconkatabibloncom,
Alpheios also is available for Chrome/Chromium.
Julius Tomin owns a website (http://juliustomin.org/home.html) that features a number of items concerning Ancient Greek. Of most interest to me is a substantial number of readings. There are readings of 16 dialogues and of the Seventh Letter of Plato, as well as some readings from Aristotle, Homer, Xenophon, Isocrates, Alcidamas, Lysias, Pindar, and the New Testament.
I sampled his reading of Phaedo, 57a1-58c5 (2:39 minutes), and found it clear and understandable.
With a couple of exceptions that he notes, Tomin’s pronunciation is in accord, apparently (he does not quite say so specifically), with the CD “Speaking Greek” produced by the Joint Association of Classical Teachers, and published by the Cambridge University Press.
Tomin is Czech. Here’s Wikipedia’s bio of him. https://en.wikipedia.org/wiki/Julius_Tomin