Marc, I haven't seen this site before. You have a very impressive list of links to ebook and audiobook sites.
I want to contribute. I'm happy to proof-read a book - now I just have to choose which one. I'm interested to know what format the final product is and hope it's downloadable and suitable for a portable device:
Quote from your website: "Finally the text is massaged into a pleasantly readable format fit for online reading."
Here's karma for you. If I could give negative karma to Mathlete, I would.