So you don’t want to gain Experience while going through Outland and Northrend content, because you are enjoying the level 60 dungeon content and PvP with your guild.  Or simply wish to stick with lvl 70 dungeons, and not gain experience beyond that.  Blizzard seems to have heard the petitions for a lvl 60 or lvl 70 only server—except you stay where you have always been.  Enter the Experience Eliminator.

You can find him at the Battlemaster Room behind the Throne Room in Stormwind’s Keep (named Behsten); or at the Hall of the Brave in Orgrimmar’s Valley of Honor (named Slahtz).  The cost to stop gaining XP is merely 10 gold.  If at any time you wish to restore gaining XP just talk to him again for another 10 gold.