Here in the San Francisco area there are a lot of cannabis clubs selling medical marijuana and some of the clubs will actually have 50-60 strains to choose from. Even if you don't have access to the clubs you can still find quite a few strains out there.

Lately a couple of mega-potent purple indica strains, Purple Erkal and Grandaddy Purple, have been real popular. Right now my guy has a trainwreck/purple erkal crossbreed which sounds really nice since the trainwreck should take away some of the erkal's knock out effect.