I've converded a couple of multiplayer Star Craft maps into single player. But only a few actually worked (like the Cats vs. Mouse, which was almost done, but I didn't had the time to bother finishing it). Once i tried the UT editor but after I couldn't put a stairway on a diffirent place than 0.0.0 i gave up and didn't ran it since.
Oh, and I mostly enjoy mapping for LodeRunner 1 & 2 (once I remade the whole Black Marsh part of Hexen 2 with both versions and that's about the size of Surface Tension and a little bit of Questionable Ethics in HL). Those monks are crazy!