I think anyone who has an iPhone has heard about the app
Stanza which is an ebook reader. There are already a couple of these around but Stanza was the coolest because it was customizable, had a great interface, is free, and allows you to download books straight from the app (I was sold at free). Unfortunately until the most recent version (1.6) it was plagued with random crashes, especially while downloading and browsing catalogs. This newest version however is the stuff of dreams! It hasn't crashed on me yet, at least more than what my own stupidity called for.
But the coolest part is this, you can put your own ebooks on it! That's right, it allows you to point to any catalog or even direct url to download a book. By the way, Stanza supports most of the ebook formats out there, including the Sony and Kindle formats. Having heard that the Stanza Desktop app is a mess (and plus who needs to download 50MB+ for not very much functionality?) I found something interesting called
Calibre, which, in addition to handling format conversions, also has a web server and book manager tacked on. The web server not only has basic file transfer and browse functions but also a stanza catalog (which appears to be a xml file). The program is in python which means it's pretty slow, but it's also easier to develop for, so high hopes for future functionality. With Stanza and Calibre together, the possibilities are boundless.
The iPhone can finally fulfill my dreams of carrying a mobile library ♥_♥