I have some decent links that are worth sharing.
First off, the Perseus Project is an absolute must-have. You can read the classics in both English translation and in their original Greek, Latin, Sanksrit, or Arabic. The site also includes online versions of many popular lexicons.
The Online Medieval and Classical Literature Library from Berkeley:
Which links to another favorite site of mine, the University of Virginia e-text library:
From this site comes this page, which has links to collections of western European literature by language:
Including my personal favorite, CELT, where you can find many Old Irish texts in English translation and many more in their original Old Irish (there are also some Irish texts in Latin):
A searchable New Testament, in Koine Greek:
The entire King James Bible, in English, from UVa:
The definitive Beowulf page, with the full text in Old English and Modern English, with maps and images, fully annotated (you can find a more basic version at any number of sites also linked to here):
Another good resource for anyone reading Beowulf is this thread
from the Tolkein Online forums. The thread starter is an Old English scholar that is very helpful, and though the thread never really took off, you could always revive and learn a lot from this guy. On a side note, the One Ring forums are actually a pretty good resource in and of themselves. While there are plenty of Tolkein geeks that don't know the first thing about literature outside of fantasy registered there, there are also some very intelligent and scholarly people who are well-versed on medieval literature. Of course, if you are a Tolkein geek and want to learn some Elvish, there is no better place to start than their language forum.
The Internet Sacred Text Archive:
And, of course, the indispensable Project Gutenberg:
If anybody is interested in constructed languages, both fictional and those designed to be used, this is a great resource, with links to every artificial language imaginable:
Also, the archives of the CONLANG mailing list: