When I started planning to teach 150 online, I immediately started thinking about my teaching toolkit. It was a very easy decision to use Google Apps for our collaboration suite (and IM tool) but I struggled for a while to determine what my aggregators would be. Needs included wiki and blog which could be shared in the easiest way possible (not requiring another account) RSS out and awesome clipping abilities. And so I'm using Google Sites and Amplify. So far, so good. :)
See this Amp at http://amplify.com/u/95iu