All the apps are on the android market, which you can only access through the phone as far as I know, and there are tons of homebrew apps, some are awesome while some its like some 12 yr old wrote heh. If you already use google calendar then your phone will sync with it so you can add stuff from either and it will show up on both your phone and on the internet. The sound quality is good I’ve found, its better than my last phone for sure! Comes with a head set for phone calls too.
You can see the top 100 apps here, but they don’t have a description and most names don’t really tell you what the app does heh. http://atrackdog.a0soft.com/index.php?view=weekly
edit: Oh and all the apps are free pretty much