Boston - Peace of Mind was great, at some point they should use Boston's "Don't Look Back"... Actually the very first Boston album "Boston" should be used. It is a Greatest Hits album in itself, it's just too good.
Anyway I found myself reallying enjoying this episode, while I have liked each episode thus far (Amy Acker anyone?) this one just really I think let the show hit it's stride, I can only hope it gets even better from here. The episode had some good thrills, chills, laughs, and the relationship between Sam and Dean just keeps getting better, especially I'm assuming as the actors spend more time together.
Can't wait for the DVD of this, hopefully they can secure all the music rights, though where they are using almost all 70's rock (in which the bands haven't been heard from in ages or haven't been cared about in ages, I'm sure they're happy that someone is recognizing their work) they shouldn't have too much of a problem, unless they try to go for something like Led Zeppelin.