SF Nightlife
Frodesign's City Guide lists several bars, etc.
Downtown
Local Edition - in basement of old Hearst building (former publisher of SF Examiner)
Bourbon & Branch - speakeasy
Ruby Skye - nightclub
Redwood Room - upscale lounge at the Clift Hotel
The View - lounge with a view at the top of the Marriott
Tonga Room - old school polynesian-themed bar in the Fairmont (Nob Hill)
Top of the Mark - great views from the top of the Mark Hopkins Hotel (Nob Hill)
Mission District
Latin American Club - very popular, strong drinks
Cafe Revolution - live music nearly every night (including Monday night classical!)
El Valenciano - Tango Tuesdays, etc.
Amnesia Bar - rec'd by Yoshi
The Marsh Youth Theater
Radio Habana
Pi Bar - they open at 3:14 PM every day. Get it? (Also good microbrews & decent pizza.)
Hayes Valley/NoPa
Smuggler's Cove - NoPa/Western Addition, 650 Gough (@ McAllister), 415-869-1900, consistently rated one of the best bars in the City, Puka Punch is on 7x7 Magazine's Things to Try Before You Die list.