I don't know of any free ones. There is one that you can download from http://www.logos.com/products/details/3320
, that is only $30 US. I have a copy myself. It has an interlinear with the Greek in the original order, and the English matching the Greek order. It also has a separate non-interlinear English-only version, in English word order, of course. The best part is that it also lists parts of speech and lexical forms for the Greek words in their own separate lines (four lines altogether). So it's basically a word study version of the Iliad. Very nice if you're having trouble "reverse engineering" the lexical form of a verb from its conjugation, or if you remember the lexical form of a verb but can't remember which conjugation you're looking at. I don't usually buy downloadable content, but the word study capability made it worth the money, IMHO.
Caveat: It comes with a special reader that you would have to install; it's not just a PDF file. I had a little trouble with the installation, but the customer support was good, and I haven't had trouble with it since.
NB: I do not have any affiliation with this product, other than having bought a copy.
I, Lex Llama, super genius, will one day rule this planet! And then you'll rue the day you messed with me, you damned dirty apes!