I just bought a cumbus (pronounced "choom-boosh") this weekend; it's sort of a cross between a banjo and an oud. The cumbus is a relatively new folk instrument of Turkish origin, with six pairs of strings in the style of a 12-string guitar.
Those sound really cool. Was it pretty straightforward to learn? Did you find one at a store to play before buying?
Basically, my girlfriend (who plays guitar in the band I'm in) and I went to Andy's Music in Chicago on a lark, and I saw the cumbus in a section of the store where they keep all the unusual stringed instruments from other countries - ouds, charangas, etc. (cue J. W. talking about "pipi drums" here). It essentially crawled into my lap and insisted I play it. The more I played around with it, the more interesting the instrument seemed to me, and I couldn't stop thinking about buying it and learning how to play. A couple hours later, I bought it and took it home and now the calluses on my fingers are KILLING me (in a good way). It's still taking me time to learn, since I'm a drummer at heart, and my knowledge of guitar is pretty mediocre, though I used to play guitar in previous bands. Getting used to a fretless stringed instrument is difficult, but once you can perceive where the intervals are, you can put stickers on the thumb-side of the neck like I did and sorta cheat to find the right notes. Figuring out chords is a lot harder, since the tuning is so unlike a guitar's and I'm used to easily finding barre chords and modifying the fingering in chord shapes to create sevenths and diminished chords and such - the cumbus is a whole new world compared to that. Still, I'm determined to get proficient on the cumbus by January - I have a solo gig at an experimental music festival and I want to use it in my set.