re: Movies that changed the way you think about songs.

As far as pop/rock songs - obviously films like The Graduate and Butch Cassidy and the Sundance Kid made some ripples, but more modern films tend to have more of a musical sensibility.

Tarantino's films Reservoir Dogs and Pulp Fiction did amazing things with songs. Marty's films always do interesting things with music, but Goodfellas remains his opus. Not a song, but every song in it is influenced by this.

I give Grosse Point Blank an honorable mention here - scored by Joe Strummer, it was expected, but an excellent use of the indivdual songs, to the point I generally recall the film when I hear a song from the soundtrack. The Farrelly brothers also did some great things with pop/rock songs in their films.