The most popular gem on the Armory is the Runed Scarlet Ruby. (I'll pause a moment for all your dramatic gasps of shock.) It's almost three times as popular as any other gem cut, presumably because the +19 Spell Power gem is worthwhile to the largest cross-section of characters: any spell caster. (Strength gems only really work out for the three plate-wearing classes, for example, while the rest of the physical types tend to rock raw Attack Power.) A close second to the Runed Scarlet Ruby, according to WoWPopular itself, is the Runed Cardinal Ruby. The epic level pattern is probably slightly less popular because the epic gems are more difficult to come by. There will be proportionally more alts and dusty characters wearing the old blue-quality gem.
The next most popular gems are the Solid cuts of either the Sky Sapphire or the Majestic Zircon. The Sky Sapphire is actually much more popular, but I'm guessing it's for similar reasons as the Scarlet Ruby. It's cheap and easy to get compared to the only slightly better Majestic Zircon. This +Stamina gem probably ranks so high because every tank wants as much Stamina as possible . . . and so do many PvP players. The cross-section makes Stamina a very attractive gem stat. (I guess it'd only be completely useless to those players who never, ever die and are somehow nearly immortal. Note that I'm not advocating Stamina over your usual powergame stats, I'm just saying it's not total slop. Dead rogues do no damage.)
The third most popular gem is the Bold Scarlet Ruby. If you got the materials sitting around, expect its epic counterpart -- the Bold Cardinal Ruby -- to go for similar big bucks.While I pointed above that only three plate classes get the big benefit from Strength. But those three classes are immensely popular. So the sheer raw number of people playing death knights, warriors, and paladins drive the demand for these three gems up through the roof.
Blacksmiths get a little lucky in their crafted gear choices, since they get to make everyone's weapon. Healers, DPS, and tanks can all find some good stuff from the blacksmithing trade. Still, I bet you can guess the single most popular blacksmithing item still to this very day, right?
If you guessed the Titansteel Guardian, you win yourself a prize. It can service all the healing classes, as well as providing DPS items for all of their casting DPS specs. It goes both ways, you see. Other than that, the next two popular items for blacksmiths are the Tempered Titansteel Helm and the Spiked Titansteel Helm. I think these two items are so popular because of the relative difficulty of picking up a hat until you have sufficient Emblems of Frost, and folks want the quick headstart on gear. (Get what I did there?) The Spiked hat does have a lot of tasty hit rating, as well, which will make it serviceable to plate DPS classes for a very long time.
All of these items are still good for bootstrapping someone into a raid, and they're relatively quickly and easily made for the cost of their materials. That kind of longevity is going to keep these items relevant, even in the current Icecrown Citadel environment.
Leatherworking and Tailoring
Leatherworking and Tailoring both have the same benefit: they provide relevant enchants to even the very highest tier of gear, so they haven't dropped off in value at all. I already talked about these items a great deal a few weeks ago, and I don't want to rehash that territory. Check out What to sell, what to sell.
In a radical change from normal operating procedure, there are a few very clear winners for most popular glyphs on the Armory. According to The Crafter's Tome, the four most popular glyphs on the Armory are Glyph of Unburdened Rebirth, Glyph of Raise Dead, Glyph of Horn of Winter, and Glyph of Levitate. So there we go. If you're a master of Inscription, you have a good target for the four most popular glyphs to list on the Auction House.
Engineering only has so many saleable materials, two of which are the obvious Icecrown arrows and bullets. The Armor Plated Combat Shotgun is still amazingly popular on Armory characters, as is the Heartseeker Scope. While hunters don't seem to still be the default character class for new players or farming characters, they're still very popular. These crafted staples of hunter gear are still valuable to folks who aren't rocking raid gear.
Explanations for Popularity
The first and obvious example for why many of these items are still so popular has to do with the nature of alts and alting. While you want your secondary, tertiary, and even quaternary characters to be in viable, feasible gear, you're not going to go hilt-deep in trying to equip them with the very best items. And there are so many hours in the day!
So if you want a fresh-to-80 character to be viable without running a bunch of old instances and raids, crafted gear can still give you a quick jog up. If you list a Destroyer on the Auction House for 900 gold, for example, that's not a lot of cash to someone who just wants to get their brand new death knight viable as fast as possible.
Secondly, it's easy to forget that there are millions of players in WoW. This could be hard to believe for many of us, but there are people who don't like raids or instances. For those folks, these crafted items will be the best gear they'll see in Wrath. While it might be below an Icecrown raider's preferred iLevel, it's all still pretty awesome to someone who'll barely see the inside of 5-man isntances.
Thanks to The Crafter's Tome and WoWPopular for the data!
Each week, Insider Trader takes you behind the scenes of the bustling sub-culture of professional craftsmen, examining the profitable, the tragically lacking, and the methods behind the madness.