This is little tool I threw together for my own item-comparing convenience. It's based on what I was talking about in this post:
http://elitistjerks.com/567618-post102.html
(I fixed the inaccuracy about the two-roll system). It's not intended to be a replacement for the larger Mage spreadsheets, simply a useful estimator of relative values of various stats in typical situations, which is often all you need. It outputs the value of 1 point of each stat in terms of spell-damage equivalence (similar to AEP for Rogues), in the context of either Frostbolt or Fireball spam.

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To use:
--In general, shaded cells are meant to be edited.

Input your current stats and talents, and buffs you wish to included in the left box.
--The stats should be read right off of your character sheet while unbuffed. For example, the sheet assumed the bonus from Mind Mastery is included, and won't add it in later.
--Many DPS talents aren't included. They're not relevant to this calculation (i.e. Piercing Ice).

Select Frostbolt or Fireball.
Read the box labeled "spell damage equivalance" for your stat weights. You can use these for quick and easy gear evaluations.

You can use the gear-comparison box to compare two items. All it does is multiply and add for you.

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Feel free to note any corrections; I've only spent a few minutes on it thus far.

That's semi-intentional. It seems more useful to have a value than to simply overwrite with a 0 when you're over cap. Regardless of what you get a from a spreadsheet, the hit cap is an annoying issue that everyone has to deal with themselves anyway when selecting gear. Also, the value apply just as well to losing a stat as well as gaining it, which could still be useful information. I added a "hit left to cap" box.

This is very awesome and much more user friendly then things I've worked with in the past. Thank you.

Well the like its been said, need a toggle for the Hit Rating for when you get to the cap, but the biggest problem I see with all spreadsheets and the way haste rating is calculated is that it doesn't drop your crit rating down when you swap an item out.

The sheet for me is giving a 1 haste is a 1.367 damage converstion, but for my normal raiding gear in order to get haste, I lose crit rating. Need to find a way to fix that.

You're missing the point though. It bases the values it returns off your current input, and if you have no input for a slot, it grossly overvalues it because in order for you to gain that stat, you need to lose something else, MOST of the time.

I'd tell you to look at my armory, but I have no idea whether it'd be broken for you or not, but it's broken for me. I know that there is not one single piece of gear on me that I would be able to replace, get haste, and not lose crit.

The formula's on the sheet use your current hit/crit/damage/haste to value the further gains, but in reality, you lose something to gain, at my level of gear, which is why these tools are grossly inaccurate for full T6 gear.

So instead of considering just the stats on the potential upgrade, you should consider the net dps change by way of the net stat change.

For example, if you can only pick up 1 haste rating at the expense of 1 crit rating, then the relative (that is, percentage) dps change is just the sum of the individual relative changes that the stats impose. If 1 haste increases DPS by X% and 1 crit rating by Y%, then adding 1 haste at the expense of 1 crit increases DPS by X%-Y%.

Making this calculation part of a tool is all well and good; not including it, however, is not grounds to say it is "wrong" or "broken."

The way this tool works is by saying, ontop of your current gear, such and such is equal to such and such, not helpful when determining what piece of gear is the best. What type of tool this is helpful for though is to tell us what to go for after our current gear is set.

We already see by the Mana Attuned Band from ZA that it, for DPS is miles ahead of all other rings in the game. So we know that blizzard is going to start making items which have haste, crit, damage, and hit at some point, but the flaw now is that most haste items stacked the haste, damage and stats, leaving out the oh so needed crit and hit.

Doing some very rough math, mantle of nimble thought is better or at least somwhere close to T6... Not sure about if you actually go to vontre's spreadsheet and get accurate numbers, but at the end nobody in his right mind would give up 4/5 T6 even if mantle of nimble thought is worth 10-20 more dmg or whatever, especially when other pieces are better to replace your 5th T5 pieces and shoulder is actually one of the easier pieces to get. Badge reward bracers also seem (again with rough numbers) superior to the ones from al'ar. Badge reward pants seem better than spellstrike too (and supply more HP on top) if you can at least gem for hit elsewhere and don't use the spellstrike hood anymore.

Is haste gear "omgincredible"? Probably not, but it's definitely not making horrible use of the item budget, as it seems superior with at least some approximate math. Again if you want to be sure remember to go to a more accurate spreadsheet to really compare but I don't see why people automatically rule haste gear out "becuase it doesn't have hit/crit".

Note that a good generalization for hit is 1 hit = 1 dmg, as many would be at the point where they're patching up their lack of hit rating via 5 dmg 4 hit gems, which means for every hit rating you lose on an item you actually lose 1 dmg from the gems and not hit rating. Of course you can do this much more accurately by looking at it piece-by-piece, but I find this a good general guidline to approximately evaluate items.

I really don't think the values of hit vs dmg can be calculated via which gems people are using - hit should ALWAYS be valued as if you are below hit cap when comparing pieces of gear. Although hit cap is relatively easy to achieve - you still need to compare which pieces of non hit gear are giving you the biggest bang for your buck vs their equivalent hit pieces.

If you just evaluate hit as if you're not capped, you'll go over the cap. Of course you need to get the "max dps via dmg/crit/haste" while maintaining hit cap (with exceptions being that you're very close to the cap, for example if you're 2 rating short of the cap it's not worth it to swap a 9 dmg gem to a 5 dmg 4 hit gem). However, in general, if you do that, when you drop an item with hit on it for dmg/crit/haste item, you will usually find yourself, more or less, losing 1 spell dmg per 1 hit rating somehwere else. So while this is obviously not accurate, evaluating 1 hit as 1 dmg gives a pretty decent approximation for the item's value when your at a gear level that still gems for hit.

Of course if you want perfectly accurate values, you go to a better spreadsheet and see. But if one item is approximately way better than another, then if you do more accurate calculations it's extremely unlikely for the worse item to suddenly be better. If they're close, however, more accurate calculations can actually turn it around.

Yeah 8 hit gems are practically never needed. If you get gear of any reasonable quality, you'll hit cap with socketing 5 dmg 4 hit gems.
If you want to evaluate gear *accurately* you don't look at the "uncapped" value of hit, becuase then you'd be stacking hit way beyond the cap. To get accurate gear evaluation you go to something like vontre's spreadsheet, put every possible gear combination that's available to you in there and see what gives most DPS... there's no way around it without being less accurate. However if you pay attention to realistic gear choices in this game when you're at a level where you're still gemming hit, you will see for every hit rating an item is lacking, you will need to lose approximately 1 spell damage somewhere else to stay hit capped and dps-maximized.