The only ones I know of are Startup at Berkeley and various video game developer meetups. WWDC and GDC are the only two conferences I currently go to. I'd be grateful for any specific recommendations! :)
Mayfield Fund/First Capital Entrepreneurs Helping Entrepreneurs event (great event last night!)
Techcrunch parties
Google Technology Users Group
Startup School
HN meetup (There hasn't been one in a while)
YC/Startup parties (Heyzap, Remail, Vark the past few weeks)
Twitter API meetup
IPhone/Android Meetup
Startup Weekend
Google Campout
Google I/O
and so much more.
Some are paid but all are open to anybody.
TechCrunch parties <- how do I get in on that?
YC/Startup parties <- ditto
Entrepreneurs Helping Entrepreneurs event <- this sounds great, but how did you hear about this?
Lean Startup meetup <- this looks great! I will definitely be at the next one. Thanks. :)
YC/Startup parties: Some people I know RSVPed on Facebook. I also follow several Twitter accounts of YC founders.
Entrepreneurs Helping Entrepreneurs event: Saw it on Techcrunch. I applied and got in.