Questia Media has released a library of over 5,000 books for free access on its Web site. You can get started browsing at http://www.questia.com/publicdomainindex .
You can page through, read the text, and search, but if you want to do things like highlight pages, you’ll need a Questia account. Despite the fact that access to these books is free, Questia itself is not. (There is a free trial available but it’s a trial.)
Since school is starting, this would be a quick place to find and search the classics if you’ve got a paper to do. Of course you’ve also got Project Gutenberg…