We had our Halloween wedding at the Twentieth Century Club in Oakland.
It was super affordable, gorgeous, and the staff is great. Here's the link: http://www.thetwentiethcenturyclub.com/weddings1.html
Photos of our wedding are at http://www.flickr.com/photos/10911748@N08/sets/72157625336643763/
Here are the other places we looked too: http://www.delicious.com/jrmynt32/weddingvenue
Click on each tool to see a sample.