I just found a great website called Korea Gig Guide - it is a listing for live music in Seoul. According to the website's 'about' page it was founded by and is run by expats who were interested in Korean music and wanted to know when and where live gigs were being played. They say that they also list things about art events, cultural things and anything they find interesting.
They have bands listed like ...Whatever That Means, Geeks, Rux, Skasucks to name but a few.
I think this could be a great resource so make sure you check it out. I've also added it to my list of links on the sidebar for future reference.
The website address is http://www.koreagigguide.com/