Here's some examples, I'm going to post links to these commercials as soon as I'm not at work where the internet is the speed of molasses.
-Miller Chill commercial with a song by the Dodos called Fools.
-Either another Miller Chill commercial, or something similar that uses one of Santigold's songs.
-That new All commercial with I'm Cool Like That from the Digable Planets.
-A Geico commercial with that wonderful Royksopp song, Remind Me.
-One of the first instances of this (that I noticed) was an Outback commercial that completely rips off Wraith Pinned to the Mist and Other Games by Of Montreal.
These are the only ones I can remember off the top of my head currently, but I plan adding to this list, and if anyone else can think of any, help me out!
Also, as soon as I figure out how to, I want to post links to download some of these songs and others because they're excellent.