Time RXS are a serious alternative, with much more adjustment than either Look Keo's or Shimano spd-sl.
I love the angular and lateral float which can be adjusted, also has the ability to alter Q factor by swapping cleats from one shoe to another, extremely positive release and step in, low stack height keep your foot close to the pedal axel.
http://www.bikesportmichigan.com/fea...xspedals.shtml