Back in the day I briefly flirted with drop bars. John Tomac was riding them, the all-in-one bar-end/handlebar combos were just coming in, and there were some interesting extended handlebars in road time-trialling, so I thought I would have a go. I took an old pair of dropped handlebars, cut them off at the brake levers and turned them upside down. I don't have any photos, but the effect was a bit like this:
It didn't work for two reasons. The first was that I put it on with my long-reach MTB stem, so it meant that you were riding with your hands much further forward and much closer together than normal. Steering was much too jittery over cross country, although it climbed brilliantly. The second reason for it not working was that the handlebars I used were just a cheap road set, and not strong enough for off road riding, and so they snapped as I was riding! Fortunately I was able to use the brake lever attached to the snapped-off handlebar and stop the bike before I did myself an injury. I never re-visited the idea, but I think with the right stem it could work. I certainly noticed an improvement on some rides, especially uphill sections.