Skilling up weapons can usually be a real pain. Even if you fight significantly lower-level monsters, you're still constantly clicking away to chase them down, and, in some cases, waiting for them to respawn.
There is one place in the game that I have found this to be untrue. Be it a glitch, or just a friendly hand from Blizzard to those who stumble upon it, there is a place in Eversong Woods down the Dead Scar where lvl 5-6 skeleton mobs respawn immediately, and in the same place, no less.
The re-spawning skeleton is about a 20 second walk south from where the Blood Elf rangers are posted at the north end of the scar. You'll have to do away with a few before you figure out which one has the immediate respawn, but once you find which one it is, you can just relax and max out that weapon skill with minimal effort. Since the skeletons respawn in the same place, you're constantly hitting something, and when you're over about lvl 15 or so (and your skill raises high enough to hit often), they're 1 hit kills.
On my 42 BE priest, I found a dagger that I wanted to use, and since I haven't used daggers since around lvl 15, my skill was very low. I maxed it out in about 30 minutes. Trying it somewhere else, chasing mobs, and losing interest, it would have taken over an hour or so.
An added benefit of this is the linen cloth that drops. Depending on your server, a stack of linen can go on the Auction House for anywhere from 25-50s and in 30 minutes of constantly killing mobs, you're bound to have a few stacks to get rid of. The only drawback is that since they die in the same place, they are more difficult to loot, especially if you're selective about what you take off them.
Great for lower lvl weapon skilling. Productive and profitable.