My personal favorite database site has recently updated their item listings with a new feature. While not currently listed on their under development page, Wowhead has started listing the items in their database with the combat ratings converted into percentages, much like another one of my favorites, the RatingBuster addon. You can take a look at the picture above to get an idea of what I'm talking about. In this case, the Veteran's Band of Triumph has +22 critical strike rating which converts to a +1%critical strike chance at level 70, while its +22 resilience rating converts to -0.56% critical damage taken (among other things).
Undoubtedly this relatively small change will make the site even more useful. Rating conversions are especially helpful when comparing gear choices and attempting to decide if a particular item is an upgrade or not. I know I'll be utilizing this new feature when doing just that.