I've been wondering what mod people have which displays the % (crit, hit, etc) on an item tooltip in addition to the rating.

RatingBuster on WoWInterface

I use it and love it.

The author updates it frequently here if you dont mind Betas. You can also change the level at which it makes conversions too if you're into that sorta thing (ie: you're on a L1 bank alt and click an item with +30agil, it wont display something obscene like 300% crit for a level 1 but rather the appropriate crit % for a level you choose like 70). Lots of cool stuff. =)