Last night I finally collected enough leather (3+ stacks) to move up another 5 points to 345, so it's time for a new leatherworking post. For this range you'll need 12-15 pieces of knothide leather to make one item. This can take time since you'll still be getting 50% leather scraps if you haven't leveled past 65 yet. Despite the fact that my skinning is at 375, I'm still unable to reliably get full knothide leather from level 65 mobs.
You get two new trainer recipes at 330: the Thick Draenic Vest and the Wild Draenish Vest. Both of these recipes and the Scaled Draenic Vest remain orange until 340, so you can make any of these. I tended to go with the mail armor with my crafting because it uses slightly less leather and adds in fel scales instead. Since I need to conserve my leather and I actually ended up with scales from skinning basilisks, this worked out for me.
At 335 your trainer can teach you the recipe for Felscale Breastplate and Scaled Draenic Boots. Leatherworkers have kind of a good gig here because they can make armor sets for 4 classes: Wild Draenish (druid), Thick Draenic (rogue), Felscale (hunter) and Scaled Draenic (shaman). I think this gives us more selling options than smiths or tailors might have.
From 335 - 345 I made a lot of the scaled draenic boots because they use only 12 knothide leather and 2 fel scales. I sent some to my enchanter to DE and kept a couple to sell. I'm actually selling some of my shammy gear on beta since we have players leveling Draenei now.
At 340 you can learn how to make Drums of War from your trainer. I haven't made one myself, since I'm mostly soloing, but I could see it coming in handy for groups. There are several variants of this recipe that you can buy from faction vendors, but I haven't gotten my faction high enough with the right folks yet. Unfortunately this recipe is yellow when you learn it and it can only be used by leatherworkers, so the selling potential is low.
Just an FYI, the recipes on Thottbot at 340 skill are faction recipes, odds are you won't be able to purchase those by the time you hit 340. Unless you mostly ignore your leatherworking you'll be past 340 by the time you gain decent faction with most groups. So don't plan on being able to buy the vendor recipes you see at 325+ for leatherworking. So far I've found only one non-faction vendor recipe for leatherworkers, and that was the one to make heavy knothide leather (bleh). I did get to Honored with the Cenarion Refuge and purchase a new armor kit from them (don't recall the name), but that's been it so far in terms of recipes. There don't seem to be many factions with recipes for Leatherworkers at Friendly rep, so you'll have to hit Honored or higher with someone to buy new recipes from them.
One other bit of info I wanted to share with you guys, it seems that all professions now have specialty BoP recipes that are supposed to be just for the crafter to make themselves. For leatherworkers this means rare leather armor in your specialization. For blacksmiths there are specialty trainers in Shattrath who will teach you these new recipes, but I found no such trainer for leatherworkers. I had to travel all the way back to Feralas and speak with my original trainer. Luckily Kaliope is Tribal - so she was able to get a recipe for the Living Crystal Breastplate. There are a few others as well, one for level 45 druids (I didn't bother training that one) and a 3-piece epic set of Windhawk gear for level 70 folks. I think it's great that Blizz is giving us epic recipes from our trainer =)