Big Agnes Q-Core SL sleeping pad.
Many air mattresses cut weight by going paper-thin, which is fine only if you don't mind sleeping with sharp rocks digging into your spine. Though still a scant one pound, the Q-Core SL is a full inch thicker than normal lightweight mattresses. Nice touch: The outermost air chambers are larger, to prevent you from rolling off the mat. [From $140; bigagnes.com]