I loved the Muls in Darksun.
Dragon Magazine did a conversion to 3.5 for them not to long ago, that seemed pretty decent. That and there is the www.athas.org you can pull from. http://www.athas.org/releases/ds3/ds3_r6.pdf
From page 16 of that document.
Extended Activity (12 hours hard strenous without fatigue)
Nonlethal Damage Resistance 1/-