Also I've noticed that this is geared toward there being 1 artist/band at each show. This might be different for different genres, but here in NL the Drum & Bass scene has like 5-6 names playing at each event so it is a bit tedious to have to enter each one manually. Again I think Facebook event integration would be a great solution to this issue because the official events have all the information about the concert if you can manage to recognize the relevant information in each post.
I think Facebook probably has the most complete summary of events across all genres if you can find a way to parse out the non-concert related events. This is probably pretty hard to implement well, but might work out with a smart enough spider crawling Facebook.