Having good luck using Calibre with iPad.
The Stanza app works well enough although the screen is somewhat fuzzy in 2x mode since it is an app designed for the iPhone.
I've been using a different app designed for the iPhone and iPad called ReadMe ($2) at
http://itunes.apple.com/us/app/readme/id335763726?mt=8
While Stanza recognizes Calibre's content server--at least it does for me-- from Readme I had to access Calibre using the web option. On the Mac, go to
http://yourcomputername.local:8080/