I love my Classic Aero Designs Sportsman seats, but I always wanted headrests. Don't ask me why (I'll probably tell you I like the look of them, and then get flamed for my misplaced priorities). I can't justify the cost of the Aviator seats, even though I'd love to have them. So I spent $100 and bought a pair of leather automotive headrests on ebay. Drilled a couple of holes in the top of my seat frames, added a bit of steel tubing, and voila. I think they look pretty cool. Removing them is as easy as pulling them up and out. Photo below (only one seat installed in this photo).
http://halie.com/o58.jpg
http://halie.com/o58.jpg