Phase IV Engineering (http://www.phaseivengr.com), Boulder, CO

This company private labels the Monnit equipment marked up by 30% to 300%.  Their web portal is practically identical to Monnits but again, private labeled.  They add a line of passive, RFID type sensors, including a UHF based one that can be read up to 15 feet.  (Most RFID sensors need you to be within a couple of feet.)   They have one especially for monitoring the temperature of a cow.

They specialize in adding custom sensors to their offerings.  This would be the primary reason to work with them versus Monnit or Mojyle.