A lot of the so-called "mashups" that were all the rage a few years ago usually struck me as crass and unnecessary. However, there are a few that just clicked on a deeper level. One was the Beach Boys and Spacemen 3's Ecstasy Symphony which I had on my computer in college. That one has since vanished, as did the track below for a bit, but I managed to recover it from Fernando at My Own Language.
Superpitcher & Pet Shop Boys- Dry Heroin
A combination of "High and Dry" and one of Superpitcher's earlier successes, "Heroin." The two work together beautifully, and I've been listening to this on repeat. If anyone has a better version, do let me know.