I don't know if you have spent much time listening to Indian or Hindustani slide guitar music, but it is pretty cool. Actually, you'd have no idea just from hearing it that it's played on a guitar rather than a veena.
I always thought it was the sole province of Vishwa Mohan Bhatt, since he invented the instrument, but I gather that there are some others out there. If you go to that Bhatt website (or directly here) you can see a picture of his "Mohan Veena".
I just started to think about this music again because somehow I stumbled on this Mohna Veena for sale on ebay. I actually have no idea how I got to that particular page, call it the hand of destiny. A bit out of my range, to say the least, but cool that it is available.
Someday I'd like to get serious about Indian music, what incredible stuff it is. For now I have a sitar gathering dust. I did practice it for a time but the extensive tuning required at any one session ususally drove me back to the banjo. You don't even need to tune one of those damn things.