In reality though, the martial arts in Korea just aren't fit for MMA. Tae Kwon Do, we've already discussed. Hapkido uses joint locks and various short range weapons for close combat. Useless in kickboxing. Gumdo, swordfighting, useless. Taekkyeon, basically the Korean capoeira; useless. Koreans are also very good at judo, which is useless in K-1. The one thing that might be useful is American boxing.
There isn't much, but yeah.... most Korean martial arts just aren't meant for MMA. The one thing is that they are quite flashy and impressive to watch. 720 kicks, 900 kicks, pretty cool to watch. If anybody wanted to learn a real self-defence martial art, I probably wouldn't suggest a Korean one.