Gamers are finally getting to see the benefit of the close of the original as Xbox Live has released
a ton of "dead" GamerTags that were used and discarded (for any number of reasons). This means that there are many more options out there for GamerTags so it's worth logging into your console and checking the Change Gamertag option from the My Xbox Channel.
There are two major things to know about this. The first is that all of the tags aren't going to be released at once as Microsoft is going to be opening up the tags in waves which means you'll want to keep checking if the tag you want isn't available. The second is that the name change will cost you 800 points (about $10 USD) so it's not something you'll want to do unless you have a lot of cash lying around. This cost does allow you to transfer all your gamerscore, achievements, and purchased content to a new tag and will notify all your friends of the change.