We have a Super Bowl mixer coming up this weekend. Not very original, but since the Pats are in the game, it's a HUGE deal here.
Last year, one of our best mixers was a grafitti mixer. Everyone wore white tops, and had flurescent higlighters and markers. The whole house was lit with black lights, and we drew and wrote on everyone's clothes. It was a lot of fun. Only, I would recommend not writing with highlighter on your skin, because no matter how much you wash it, you may not see it anymore, but you will be black light reflective for weeks
We also had a Heaven N Hell mixer. The downstairs and upstairs was decorated accrodingly with refreshments to match. My friend's sorority went one step further, and they all dressed as devils or angels.
Anyway, good luck with your new position, and hope you have an awesome semester!
Luv in pke, Jen