So i just picked up the Fen Ring of dodge or something like that. It has a +12 dodge rating and +3 agi. Right now i have Seal of Sylvanis, +8 stam +3 str, and Fen Ring of Monkey, +5 agi and +5 stam. Should I put this on AH or equip (42 rogue)?
Personally I'd put the dodge one on AH, but I also have a vendetta against dodge. Its doesn't overly matter, cause you'll replace them soon enough anyhow.
I agree with the others here just sell it on the AH. Dodge is pretty meh for rogues.
You're 42 so you'll probably be running ZF fairly soon. There's a quest in Tanaris that rewards you with a nice ring; [wowitem=9533]Masons Fraternity Ring[/wowitem].