One of my friends asked about teaching at a university in Korea. That's when I realized that I have not put my two cents in on the process yet. So here it is. If you have questions or need advice, you are welcome to contact me.
If you have a Master's in an English related field, getting a university job could be an easy process. All you need to do is visit Dave's ESL Cafe and check out JOBS-->Korean Job Board. You can do a "Find" search with the keyword "university" to help you evade the undesirables.
From what I saw when I checked the other day, my first university in Korea, Duksung Women's University, is hiring. That was a nice entrance into Korea in a quiet area of Seoul (Suyu) and near Hwa Gye Sah, a Zen Buddhist temple.
Working at Yonsei University was a very different experience. At Yonsei, there are less hours (12) and more vacation (4-5 months). If you are looking for the ideal situation, I would advise choosing a school that offers under 12 hours, free housing or stipend, and about 2500-3200 won per month. These jobs are sometimes listed on Dave's ESL, but they will be listed on the individual university websites first.
Here are a few schools in Seoul I would recommend:
A university like Duksung, where you teach close to 30 hours a week (even thought they say 16), can be a bit much. It is also a very campy experience. If you want to just enjoy Korea and have an easy experience with free housing, a place like Duksung may be just what the doctor ordered; however, if you want to make this into a new career, I would suggest taking a TESOL training course to fatten your resume, and try your hand at some of the bigger universities.
If you decide to teach outside of Seoul, or at a school that I have not listed, then be sure to do a Google search, and a quick check on the Job Forums for other people's experiences. Some schools are run as businesses (hogwans), and the treatment of teachers is fairly poor. That is why it is a good idea to see if there is any news on the forums; it could save you the effort of submitting an application.
Another thing to consider is the passport photo with your application. You will need a nice, wholesome image of yourself attached to each e-mail or paper application you send out. If you have something that is several years old, you just might want to get some new shots and extras made in case you need them. I would also get 20 or so copies of your transcripts, FBI background check, local Police background check, extra copies of your diplomas, and a notarized form that gives a lawyer or family member you trust at home "power of attorney" to handle any financial or academic issues while you're away (this can save you a 2k trip home).
6. VISA LINK
If I had to do it over again, I would probably go right back to Yonsei University. It was a nice experience with a great support system. Then again, Duksung was nice as well. Different places, but both what the doctor ordered.
I hope this helps. : )