What to Bring
The kitchen sink
Things you'll most likely not be able to bring, but need to buy relatively immediately when you get here:
The one thing I didn't know that, if I had, would have effected my packing is that it takes at least a day for clothes to dry here because of the high humidity, even in the winter. Had I known that I would've packed more undershirts and more white socks.
For some reason I didn't bring soap, shampoo or face soap but wish I had. It can be difficult to pantomime that you want face soap. My contract stated that I would be provided with a towel but there wasn't one in the apartment when I got there. It may sound weird, but the only things you absolutely need when you get to your apartment are sheets, pillow, towel, soap/shampoo, change of clothes. If you have these you can sleep, shower, dry off and get dressed. Then you can go out and buy everything else you need. So as odd as it sounds, make sure that you have those things packed or that they are providing them. Make sure someone from the school actually follows you in your apartment so you can make sure those things are there, and if not they should rectify the situation quickly.
I've heard a lot of people say to bring over any "comfort foods," or anything you feel you just can't live without. If you live in Seoul you can bet that you'll have access to whatever you want/need. It may be more expensive than it would be in the States, but it totally depends on the item. Just do some googling for specific stuff.
Below is a list of everything I brought with me. This is probably useless, but I remember wanting to see what someone else had packed just to give me an idea, so that's why I've provided this.
What I wore on the plane (tmi?):
What I packed:
EDIT: It is now early July and I've been here almost 5 months. In that time, I've purchased the following things: 6 shirts, white socks, desk lamp, oscillating fan, Xbox 360, power strip, another belt, clothes drying rack, and other small toiletries and necessities such as shoe polish, toothpaste, Febreeze, etc.
I regret three things in my packing: deodorant, money, and books. I live about an hour south of Seoul, so in the city I'm sure you'd have no trouble finding deodorant, but I seem to only find the deodorant/anti-perspirant spray stuff which just isn't too effective. I was told to bring a year's supply but thought that was silly. However, a large stick will last at least a couple months, and 4-6 sticks don't take up that much space. Secondly, I'm a voracious reader and only brought a couple of books. While English books do exist here, you obviously don't have the same selection so bring what you need. Nowadays, an ereader is an amazing thing for just this reason. I took all the money I owned in the world, which amounted to $243USD. I got paid a couple weeks after starting work but only for a few days of work because of how the pay period was. I didn't get my first full paycheck until about a month-and-a-half after working, and had to borrow about $150 from my boss before I got that paycheck (thanks again Paul).
The dress code at my school was not what I had assumed. I had assumed business or business casual, but the dress code was casual. The female teachers, however, dressed a lot nicer than the male teachers. That may be because all the females were Korean, and most of the males were foreigners, or maybe there was a double standard, I never bothered to find out. Make sure you know how you're expected to dress so you can pack better. Even if you do ask, however, your recruiter may tell you one thing, and the reality may be another. Just be flexible.