Jerry's is my favorite record store. You can spend an entire afternoon here searching through the records without even realizing it.
It's all older used records (if you are looking for newer stuff try Paul's in Bloomfield) and if you take the time to search, mixed among the thousands of non-relevant artists you can find some real gems at a CHEAP price. I found Rust Never Sleeps and Live Rust by Neil Young at Jerry's for $4 a piece. These same records I saw at Amoeba in San Francisco for almost $30 a pop.
Take some time to talk to Jerry the owner. He isn't shy about discussing his musical tastes and will tell you if he doesn't like yours!