360voice.com has a really neat site you should check out if you are an Xbox 360 user. There seems to be a cottage industry for web sites generating reports from Xbox 360 data, but none integrate things as well as 360voice.
I have used it since April and the feature set of the site has grown by leaps and bounds since then. The longer you have been a user, the more useful the data becomes, as expected.
Utilizing the data-stream from Microsoft, as well as integrating other data and links from xbox.com, 360friendspot.com, gamerscorechart.com, mygamercard.net, 360voice.com is a great idea that keeps getting better.
The site offers an API, which they have been actively developing, plus RSS feeds. Some of the random sayings from "your" 360 are pretty funny too.
The Top 10 Most Played Games is probably the best feature offered. It only tracks games you have played since you signed up for the site however. This is a general note you should be aware of. If you have 1000 points in Call of Duty 2 and play that game after you sign up for 360voice, it will record your daily Gamer score as earning 1000 points in Call of Duty 2 that day.
That is a minor annoyance, and one that is shackled to the way the data is provided and used.
Another new feature (keep adding more guys!) are 360voice Badges. The developers have picked specific achievements or criteria that are noteworthy. If your profile has one, you get a nice badge. Matt completed 100% of the CoD2 achievements, so he gets a spiffy badge.
There are some cool (insane) badges, such as Geometry Wars 50 Days of Play.
The site has a public directory of all registered Gamertags, as well as a Leaderboard generated from those registered users.
