Hello, while searching online about the Greek novelists, I stumbled upon an interesting site (see URL below). The site is in French, but you should have no trouble finding an author of interest. From what I see, the provided texts are in Greek. However, sometimes not all books are present (e.g. The entry for Xenophon, Anabasis, has only books 1-5). Since each book entry is dated, I am not without hope of updates, and I must admit that I did not thoroughly examine the site yet.
BTW the Greek novelists are all there to some degree (Achilles Tatius, Longus, and Heliodorus). There are also a great deal of other authors, from Achilles Tatius to Xenophon.
http://mercure.fltr.ucl.ac.be/Hodoi/concordances/intro.htm
PS: By chance I got hold of a Byzantine Greek novel (12 cent.), whose introduction spoke of the earlier Greek novelists. Hence this search. I didn’t think that the Byzantines actually wrote novels!
EDIT: The ancient novelist Chariton is there as well.
Very nice seems that site.
Have you read Bion or Moschus?
By the way, don´t you know about any site with the opera of Callimachus (Hecale) or Arctinos of Miletus (what remains)? I am seeking for they and I don´t found anything.
Cordially,
? Γονζαλλοπιζ (genitive of my name: τοῦ Γονζαλλοπιδος) 
Thanks, Plukidis, for your useful information.
Plukidis, I have good news. I´ve found a small part of Callimachus´ Aetia… but it´s difficult to read for me.

http://www.csad.ox.ac.uk/POxy/papyri/vol64/150dpi/4427.jpg
hehehe…
Nice find! But we are so used to modern punctuation and typed fonts so that reading a papyrus is difficult to impossible, at least for me. However, I suspect this would be easier to read, and maybe a library near you has it:
(search for Callimachus)
http://www.hup.harvard.edu/loeb/author.html
I have downloaded a course on palaeography. I found it at Live Search Books (Microsoft). If you don´t find it, I would send it you by e-mail.
The name of the course is “An introduction to Greek and Latin palaeography” by sir Edward Maunde Thompson (Oxford, 1912).
Χαí?ετε!
See what I found at Google books:
http://books.google.com/books?id=3q0CAAAAMAAJ&pg=PA500&dq=callimachus#PPA1,M1
It seems very well. I am going to print and work on it.
Thank for those links…much appreciated!