The theme from the old LucasArts game Zak McKracken and the Alien Mindbenders seems to be especially popular for latter-day remixes. Case in point — I was digitizing an old mixtape, and discovered I had both a basic remix and a “House” version created as Amiga MOD Tracker remixes by a friend of mine, Mark Darin (now of Monkey Island fame!).
I later created a mix of my own, somewhat inspired by Mark’s take on it; and I hear tell (on Wikipedia) that Martin Irigoyen, The Dead Guys, Puffy64 (a really slick 90s rock take), DJ Lizard, Razor and the Scumettes, the German band Glückswald, omnibrain, Daniel Strandberg, Roland Koch, and 55-cycle have all also made covers of the song. There’s also a few unattributed versions I found, like this C64 SID version, and a basic GM version. [Sadly some of those versions no longer seem to exist online. — Ed. 2015-08-13]
But the coolest version I never thought I’d heard (and just discovered in the research for this post) is the original theme. No, not the one that shipped on the C64 — the original 1987 synth version that Matthew Alan Kane recorded before he programmed it into the game. Wicked keen!
Just in case of future catastrophe, here's an copy of his site on the Wayback Machine.
For more info about the music of Zak McKracken, I recommend Zak-Site.com.