Points for guessing what film the title of this message comes from....
I was messing about with my gear and stats and gems and things recently so I thought I'd share some of the sites I use to look at myself.
Be Imba allows you to access your character on the armory (I think you must be level 70) and then tells you which instances your gear is "good enough" for and where your best source of upgrades will come from. It tells you which items are not enchanted "correctly" and what gems you should use. For me it's a good "guide", but not strictly "the law". For example, it doesn't like my +30 spirit enchant on my [Rod of the Blazing Light].
Another website I fiddle with is Loot Rank, which is described far better than I ever could describe it by A dwarf Priest in his article. I say fiddle because the theorycrafting and stuff is a bit beyond me - well, probably not beyond me, but at least beyond the time I'm willing to invest in it.
Kaliban's Class Loot Lists provide gear information for all dungeons and raids, as well as world drops. This one is great when you're levelling to know which instances you can get great gear for your character from.
Another great site to while away hours on if you're so inclined is character developer. Here you can mess about with all the gear, buffs, gems, enchants, food, drink, etc. etc. that you want and put them on your character to see what effect it might have. If I had a whole day to mess about I'd spend it here.
Well, that's all I can think of for now - as I come across more I'll let you know.
Time may be a bit short for daily posts over the coming months. The kids have finished school and I have 9 weeks of fun to come. Come September I'll probably be a shrivelled, wrinkled, hairless wreck - but so far - half a day down it's doing OK - helps that son is out over the road sleeping over in someone's tent and that daughter has a friend round. I have a cup of tea and a few minutes peace to write.
Enjoy your day all....