I see people are checking this from time to time. The links I had posted earlier were broken, but you can still browse the old tests on the TOPIK website.
The test is given twice a year: April and October. Registration is a few months before, so check the TOPIK site in late-January for April, and July for October.
The
TOPIK test is given twice a year, and might be a nice thing to show for your time spent in Korea. The next test is in April, and the nearest testing center is in Gwangju at Chonnam University (전남대학교).
There are six levels and three tests. Levels 1 and 2 are beginner, 3 and 4 are intermediate, and 5 and 6 are advanced. If you take the beginner test and score above a 70%, you pass Level 2. If you score between 50 and 69%, you pass Level 1.
There are test prep books available at the large bookstores in Seoul. You can also get previous exams on the TOPIK website. Go to
http://www.topik.or.kr/ and click on 자료실 on the left sidebar, and browse eight pages. 초(1~2)급 indicates beginner.
Before I came back to Korea this year I had planned to study hard for half the year and take the intermediate exam. I browsed through the practice exams and its really hard. There's
another blogger (some pics NSFW) whose Korean skills are light years beyond mine, and he's still at level 3, so I guess level 2 is a more reasonable goal, even with 3-4 months left to study.