As wraith808 already mentioned, Stanza. It works wonderfully in tandem with Calibre
on the PC side, eradicating the need for the crappy iTunes crap - and without having to transfer your PDFs through DropBox (which is just stupid).
Other than that, I have a few games - Plants vs Zombies, Bejeweled HD, and Lena Games Taipei
. I use the device almost exclusively for techy ebooks, casual surfing (which often means looking up stuff on google/wikipedia/imdb at night when my brain is following random chains of though), and the casual game while commuting (or not feeling quite like getting out of bed on a sunday morning).
PS: I hate crApple and how locked-down iOS is. If the Stanza+Calibre combo hadn't been available, I wouldn't have bought an iPad2. Back when I bought it, the available Android tablets were utter wank, but it seems this situation has improved quite a bit - I'd be a lot less inclined to go for an iPad today.