Since I bought my iPad a couple of weeks ago, there are two apps I use constantly. One is Flipboard, which turns your Twitter and Facebook feeds into a social magazine, which is pretty cool, but it separates Twitter from Facebook, and while it can use Google reader feeds, they are buggy at best.
The other most constantly used app is Zite. The difference being that it only shows you the links to stories in your feeds. You get none of the social context around it, your friends and people you follow become simple curators.
What’s more is that as you tell the app what stories you like, and what types of content you’re interested in’ it gets better at predicting what you will like in the future.
When you couple this with Delicious as a way of collecting and saving the real good stuff for later reading, you have a killer app.