BadukWorld is another Korean go/baduk server. It features access in Korean, Chinese, Japanese and English, and the main code is written in Java (thus runs on almost any platform).
It seems to be a very small server, compared to Korean standards (logging in, I almost always saw 800-1000 players). The highest I saw personally was a 10D player.
The server seems to be oriented towards expatriates. Playing fee is $10 per year --- really nothing, but they only accept Korean credit cards (and for expatriates, it suggest to ask some friend to pay). Software is relatively lousy; for some of the functions (i.e., chat!) to work you must install a Windows-only addon.
You can observe games as a guest.
Any comments welcome, Helger.