I bought the soundtrack to Scott Pilgrim today off iTunes cause Walmart didn't have it. I enjoyed most of the songs found in the movie, but the one problem I've always had with listening to a song after it was in a movie is I realized that it was only good in that context. Some of the Scott Pilgrim songs are that way, but most stand out on their own.  
 
All of the song the Sex Bob-Ombs sing are written by Beck and they standout as the best in the movie. With a very good opening song one called Garbage Truck, Threshold, and Summertime. Threshold is probably my favorite, cause it's featured in a awesome battle, but stands alone well. Plus it has one of my favorite lines from the books "WE ARE SEX BOB-OMBS AND WE'RE HERE TO MAKE THINK ABOUT DEATH AND MAKE YOU SAD AND STUFF!!"  
 
One non Sex bob- ombs song that stands out will be Black Sheep by Metric. It's awesome. In the movie Envy Adams sings it (she's on Clash at Demonhead). 
 
There's also a score soundtrack that I didn't buy, but I bought the Katayanagi Twins vs Sex Bob-Ombs which Threshold is played. It also has a amazing, and I mean AMAZING bass battle between Todd and Scott which is now the ringtone for my phone ^__^ and the old school Universal music which is also on my phone.  
 
I'd say get them both, only the Score one if you're into the movie as much as me. They're are both pretty legit. 
 
  

that bass battle was too, damn, beautiful.

Agreed, that damn movie was surprisingly entertaining in relatively every aspect.