Hey, eReader is also free
I like it better over Stanza as you may add a dictionary (you may have to buy one first!) searchable directly from inside the book you're reading. Also there is a find option that let's you search for a word or expression inside the complete book (starting from the first page or the page you're reading) - on Stanza, and as the books are not loaded completely but on chunks, you may only search the chunk you're reading...
...of course Stanza as a better catalogue presentation, with all those book's covers
and you may use Calibre to send epub formated books to you iPhone/iPod using the included webserver (it's dead easy
) - but I also created a simple webserver with Apache on my desktop to send my pdb formated ebooks to eReader (I did it in 10 minutes and it was the first time I ever used Apache...)...