I've just released my first book for proofreading on Gutenberg Distributed Proofreaders (international division). For those who don't know, that means that I'm trying to create an electronic version of a public-domain book, and contribute it to Project Gutenberg, which maintains a library of such things.
The book is Gesenius' Hebrew grammar, and you're all encouraged to help proofread. (Images were generously provided by David Steinberg of Congregation Adath Shalom.) If you read Hebrew, that's a plus, but if you don't read Hebrew, you can still help by proofreading the English parts of the text. If you have any questions, just ask!