Classical texts on Google Book Search
How to find other people's collections of Classical texts that can be accessed via the Google Book Search and similar mass digitization projects?
How to share one's own collection of such texts with others?
Google Books Ancient Greek and Latin Texts
One useful collection can be found at Google Books Ancient Greek and Latin Texts: "Google has digitized over five hundred ancient Greek and Latin books. We present them here downloadable as zip files of images and plain text, and as links to Google Books web pages where you can read them online in full or download PDFs. This collection was selected by Prof. Greg Crane and Alison Babeu of Tufts University, and compiled by Will Brockman and Jon Orwant of Google. Enjoy!" (from the webpage).
There is also a Limited Distribution version: "The zip files (...), containing images and plain text, are part of Google Books' research collaboration with Prof. Crane, and are restricted to authorized users within the United States. For authentication, you will be asked for the username and password of your Gmail account." This list of titles can still come in handy, though.
See also: Digital Facsimile.