Songs

There seems to be a limited number of songs that get used in new TV shows.  Last year, I think I heard "Suddenly I See" in like 4 new shows, from Ugly Betty to Men in Trees, and I can't remember what else.  This year -- I just heard the same background music in Cane that was in Chuck last week, and I swear that Gossip Girl and Dirty Sexy Money had that same cute "whistley" theme song that I can't figure out the name of and really like.  Why does everyone use the same music?  And does anyone know what the names of these songs are that I'm talking about?