I agree QT kills it with every single soundtrack. His music choices enrich every one of his movies and are a big part of why his films are what they are IMO.
For those who watched the "making of" on the Blu Ray/DVD already know this tidbit but for those who didn't, this is a cool little fact on how QT discovered the 5,6,7,8's. He was in a trendy clothing store in Japan before he had to go catch his plane and they were playing the 5,6,7,8's. He dug it instantly and asked who the band was and if he could buy the CD. They suggested going to Tower Records where he can pick one up of his own but he said that he didn't have time and was off to the airport. They said they had to call the manager to see if it was ok, and he said "ok, call him" (he stated that being that pushy and forward is pretty rude to the Japanese but the end result was worth it). He said that he knew he had to buy that CD on the spot because if not he would've came back to the states and put it on the back burner, forgotten about it, whatever; bottom line it wouldn't have happened. They sold him the CD and when he got back to the U.S. it dawned on him to seek the band out and have them preform in the film.
IMO their presence and music really shape the beginning of the HOBL scene. A few Japanese chicks that play 50's surf music to kick off a bloodbath massacre scene? How Tarantino is that?!?! And he just stumbled on this element that adds so much flavor to that scene by pure coincidence one day.