Your Top Five Favorite Social Software Sites

Via The Social Software Blog:

I’m also curious to know what social services folks are actually using the most, beyond whatever is the latest hot company we’re talking about on the blawgs…

Oh! I like lists! And I like Social Software! Here goes:

1. Flickr
2. Bloglines/NetnewsWire/Safari RSS Reader
3. iChat/IM
4. Technorati
5. Last.FM

What are your Top Five Favorite Social Software Sites?