Kevin of jkOnTheRun tested (http://jkontherun.com/2009/02/24/stanza-vs-ereader-first-impressions/) two very popular free iPhone apps for reading e-books. One is Stanza (http://www.lexcycle.com/), the other is eReader (http://www.ereader.com/). His first impressions: Stanza looks prettier and pagination works better and quicker. eReader, on the other hand, has more theme options (background and text color).

One important difference is that Stanza supports various e-book formats, including those without DRM, whereas eReader uses exclusively the eReader PDB format (with and without DRM).

Related: Best ebook reader for iPhone? (http://www.mobileread.com/forums/showthread.php?t=36903)

I love reading with Stanza. I mostly read free books from Feedbooks (http://www.feedbooks.com/) on there.

I like Stanza because of O'Reilly's Bookworm site where you can keep your ebooks. Makes downloading to my iTouch a snap.

I just wish that Sony would figure out that maybe an iphone app that would read .lrx would help their ebookstore cause. Seing how I have both a 505 and an ipod touch, that would be wonderful