Volunteer work? (Seoul)

Hi everyone,
I will be in Korea starting end of September for 2 weeks. Instead of just doing sight seeing I was thinking of maybe doing some volunteer work. I did some teaching in India and also took care of some kids in a kindergarten in Japan before. Any suggestions for Korea :-)?

I was also wondering if there are any language cafés, etc. where one can meet with Koreans and have a chat in Seoul / other major cities.

Any suggestions are appreciated

Cheers!
Stefan