Spartonian over on WoW LJ has been running some old content, and he points out something that everyone should hear: now is the absolute best time to be running the old Burning Crusade endgame. He says the contest is laughably easy with current endgame levels and gear, and yet, because we're still basically at the beginning of this expansion's endgame, there are still quite a few items that can be picked off of the end bosses in Black Temple and Sunwell (not to mention you can pick up the achievements for those places if you weren't able to down them before.
And he's right -- there are some nice trinkets still found in those old instances, and who wouldn't want to complete their Warglaive set or grab a Thori'dal from Sunwell? Sure, the stats may not be the best, but until the ammo changes go in, you can save money while soloing -- and own a legendary to boot.
Of course, when Ulduar shows up, we'll all likely be too busy with the new content (be it the raids or the Argent Tournment or whatever else you got) to go back to Burning Crusade. But now, during the downtime post-OS and Naxx, is the perfect time to go back and clean up the old content.