I won't join Best Fares, but I read the NewsDesk almost daily. They generally don't tell you who the specials are with, but you can usually figure it out. Last winter they posted $80 return SJC-YVR, but didn't say the carrier. Well, it wasn't too hard to figure it out and book it myself.

They appear to have a deal with Southwest too, because everytime Southwest does their $99 or less one-way fares, Best Fares posts $164 return on all their routes.