Photo from radiofreesilverlake
A night at Pehrspace in Echo Park is what I would imagine an art school dorm party to be like: BYOB, small room, and edgy music. There's no sign outside of this nondescript art / music house, so just look for a crowd milling around outside and you're probably at the right place.
If you are a hipster into the L.A. indie music scene, I can safely vouch that Perhspace wins the "Indie-st of the East Side Indie Music Venues" Award.
The first night I went, a guy was performing who can best be described as a one-man-band/rapper/performance artist. By the end of his set, he was on the floor spinning in circles while the crowd (50 people or so) clapped, chanted, jumped in unison, and passed around a stuffed unicorn. Anyone who stepped into the room would have thought we were in a cult. Awesome night.