Ahh, now you are talking my language. Wow so many to choose from, but I will stick to my old haunts which are mostly just tried and true joints:
1. Vesuvio, which has been around forever and which is a classic, being right next to City Lights Books and which has that great mural in Jack Kerouac alley inbetween.
2. Specs: Nothing fancy, just a cool saloon style bar that is great for hanging out with friends.
3. The Saloon: Which occasionally has live music but like all of these places is always packed after 9 pm.