California Pacific (technically it never went bankrupt because it could never get certified). It was started fairly recently (2009), a few miles from my house. It was planned to be a low cost regional domestic carrier based at McClellan-Palomar north of San Diego.
We live nearby, then. I'm just East of SD.
Yeah, I was pretty hyped for Cali Pacific too. You don't see many new airlines these days, if at all. I think the youngest are Allegiant and Virgin America, and they only exist because they're branches of bigger airlines.
Nowadays, starting an airline is near impossible.