While the Cat dozer is okay, the world's largest dozer is the Komatsu D575A-3SD, weighing in at 320,000 lbs. and sporting a 92 cubic yard blade. The attached video shows it working in Australia and it is the RC version- note the operator standing to the rear with controller. Of course, the mining industry has gone a step further with autonomous operation of 390 ton haul trucks - GPS positioned and operated by its on-board computer. Seems to take all the fun out of operating!
http://www.youtube.com/watch?v=TxxyII9ko9c