How/where to sell Xbox Live Accounts with high rank Halo:Reach stats?

I'm not sure if people can do the same thing with Xbox Live accounts as they do with gold or items in WoW or Accounts for Ragnorok. Just wondering how I can make some money from playing all these games! I'm pro status the accounts for Halo:Reach are Lt. Colonel Grade 3 700,000CR. Any tips or people actually interested in buying mucho appreciated :) Let me hear your feedback my fellow nerds.