Herbalism and alchemy are right out. They would actually be pretty useful, if I was leveling in isolation... but fortunately, I have a couple of 70+ characters, one of whom is an alchemist. So keeping Aeven stoked with level-appropriate potions shouldn't be a big problem. Plus, you know, paladin. If I need Lifeblood that badly, I'm doing something wrong.
I'm going to dismiss enchanting for the same reason - another character has 450 enchanting, and can provide Aeven with whatever enchantments she needs via scrolls. In the event that that's not a possibility for some reason, Aeven can have her more experienced sibling disenchant items for the materials to get someone else to do her enchantments for her.
While inscription is apparently a pretty good money-maker, I'm not all that interested in just accumulating cash. Jewlcrafting and tailoring are out, as well - there's pretty much nothing that you can make that isn't uncommon or better. Oh, sure, there's some white cloth items creatable by tailoring, but - ahem - she's already decked out in mail, so what's the use? There are some white gems, which even Aeven could use, but there aren't any white items with gem sockets on them.
Or... are there? Take a look at Blacksmithing. There's a number of white enhancement items that are craftable by a blacksmith, and which would be good for leveling. Plus, at 400 skill, blacksmiths can use Socket Gloves and Socket Bracer. So, while an Eternal Belt Buckle is right out, being a blue item, I could go with Blacksmithing and eventually have two gem sockets. There are only 13 white gems, but I suppose that if I ever really needed that +8 hit rating, this would be a way to get it. Something to consider, at least.
Leatherworking is out for much the same reason that tailoring is - there's really no use for it, especially while leveling, except as a money-making proposition. In fact, the only reason I can see to take it would be in conjunction with skinning, for the ability to combine lower quality leather to produce higher quality leather. Meh.
Engineering has the same attraction as blacksmithing - lots of nice juicy usable white items while leveling. Having tried leveling engineering once, though, my experience is that it's time-consuming and expensive.
Let's see... what haven't we looked at yet? Just mining and skinning. Mining, which can give you Toughness (up to a +60 stamina bonus), and skinning, which can give you a Master of Anatomy (up to a +40 crit bonus).
While it looks like blacksmithing might be interesting, I think I'll go with mining/skinning for now... and possibly drop skinning at a later date in exchange for blacksmithing. Those stamina and crit bonuses are just too tasty to pass up.