First thursday + first Friday
Once a month they have a gallery open house evening. This happens on different nights in different neighbourhoods. The first thursday of the month is in the Pearl District, right where I'm staying. I didn't get to any galleries but on 13th there was a market that spanned a couple of blocks, selling art, jewellery handicrafts and clothing. Also a couple of street bands played.
First Friday is in North East. I visited about 4 different galleries. One of them was actaully a design company here called Nemo. They had an exhibition called Furry Kamasutra. Photographs of people in animal costumes in sexual positions, along with four short films showing the story behind the photo. Reminded me of Amsterdam.