Today it is Joshua Radin's "Closer," and I cannot possibly listen to it enough. I would distill it into liquid and inject it if only I had a Bunsen burner and some glass tubing. Edit: Why am I ever NOT listening to this song?
Old 97's: "Question"
Del Amitri: "Tell Her This"
Martin Sexton: "Diner"
Fountains of Wayne: "All Kinds of Time"
Other recent non-Scrubs obsessions:
Sia: "Breathe Me" (found in a PostSecret video)
Unkle: "Lonely Soul" (from the Assassin's Creed demo at PAX)