With my friends that are on Facebook though, I can read what they're doing, they can see what I'm doing, and we can comment and talk about it. Oh, you saw a movie? I also saw that movie, wasn't it good/bad/funny/whatever?
Also, the groups and events on Facebook are just fantastic for planning things. I went on a trip with some friends from college a couple weeks ago. We all live in different parts of the country and coordinating something like that would have been a nightmare without Facebook. We made a group and used it to post all the information about when our flights were leaving, what hotel we'd be staying at. It was really really convenient.
If you're annoyed with your friends posting stupid stuff, just ignore the news feed. There are dozens of other reasons to use facebook.