The article describes iBooks (my favorite), Kindle for iPad, the Barnes and Noble eReader, Kobo Reader (from Borders eBooks), the iBis Reader, Stanza, and vBookz.
http://www.zdnet.com/blog/perlow/apple-ipad-showdown-battle-of-the-ereader-apps/13248
Tools and Ideas for Surviving (and Thriving) in Technopoly