I've heard 'talk' of some one-off contract work carried out by pilots who usually work for major airlines, carried out in areas of Africa (although I'm sure there are other areas of the world where it goes on). I'm told it usually pays well, but it seems a bit hush-hush, so you can only really find out about it by word of mouth.
I'm afraid my only credentials for this information are that I've met people who allege to have done this work...