EventBox is an OS X desktop app that lets you watch activity on the various social networking apps you use, from one convenient window. Right now, it supports Flickr, Facebook, Twitter, Digg, Pownce, Reddit and rss feeds. You can view everything in your stream, including photos, from within EventBox.
If you're completely addicted to your information stream, and you want to see it all in one place, EventBox might be worth the $20 pricetag. The UI looks fantastic, and the app features the all-important Growl support. Apparently a HUD mode is coming soon (think Twitterrific), which will make the app's footprint on your screen smaller. You might not be interested in what EventBox has to offer if you're not very active on social networks, but if you're looking for this kind of app, EventBox gets it right.