Sometimes I think about the amount of time I spend online any given day and cringe a little, but there's a lot more to the internet than just "time-wasting". You've got information, discussion, and interaction all within easy reach, all things that few other activities can provide short of actually going out and pulling all of your friends together in one place, something that's not always possible.
It's all about creating a balance between time spent on the internet, time spent working, and time spent with real-world friends. Too much of any of those three can be a bad thing.