Has anybody ever used closed cell neoprene (wetsuit material) as sleeping pads before? Here's a link to a company who sells the stuff from 1/16" all the way up to 2" thick.
You can get a sheet measuring 24" x 80" x 1/4" for less than $20. I think it may be more than warm enough compared to most other foam pads, more conforming to your body, not any more of a vapor barrier than a regular foam pad, and much more compact when rolled. It would also slide around much less if it's just bare neoprene for those of you who don't have hammocks with pad pockets. It's just a thought and when I searched the forum for this topic I didn't get anything so I figured I would bring it up. I may get me a sheet of this stuff. It might make a great foot pad.