Go to your profile, scroll down and click Look and layout preferences, then beside current theme click (change) and bam. New layouts. I recommend DS-natural as it looks the best imo. I just figured I'd share this because I don't think enough people know about it. :)
its the best because that was the theme i worked on as admin when i was.
The only problem with the other themes is that we don't get the monthly image on them.
But aside from that, DS-natural looks pretty spiffy. =^.^=