TweetDeck

TweetDeck is a desktop client for your various social network feeds. It does Twitter, Facebook, Google Buzz, Linkedin, Foursquare, and MySpace. You can see updates from all of these sites. You can update your status and post it to any or all of your social networks. It is easy to configure, and has a good number of options for things like notifications and filters. Getting all your updates in a single client is a real time saver.

Foursquare

Foursquare is a different kind of social network than Facebook or Myspace. The network relies on your mobile phone. When you  go places, you “check in” using the Foursquare application. These “check ins” earn the user badges and allow you to share you adventures with your friends. The video on their website does a better job that I can do of describing what it is. But I can tell you that it is a lot of fun, and a great way to share with friends, and meet new people.