If you maintain accounts on multiple social sites (say Flickr, Twitter, YouTube, Facebook, MySpace), consider using 8hands - a small Windows software that monitors your social circle and will bring some peace to your otherwise chaotic online life.
With 8hands, you'll instantly know (via desktop alerts) when friends upload new pictures on Flickr, or there's a new comment on your Flickr photos, or when you have private messages on Facebook or new tweets on Twitter - no need to manually check profiles on all the different websites.
Now Flock too offers similar features but 8hands, a standalone app, has two main advantages:
1. 8hands will automatically guess your top friends with whom you communicate most frequently across all social networks - so it becomes all the more simple to reach them again.
2. 8hands maintains a complete history or log of all your friend's activity. Very useful when you are looking for Facebook messages, Flickr photos and Twitter tweets ever published by a close friend.
8hands is in alpha but worth giving a try. It's been running in my system tray for a few hours now and am loving the notifications.