Ian, the Commando
Ian has become quite adept at what we call the "commando crawl." He doesn't use his legs for propulsion. Instead, he crawls forward on his elbows. Mostly, he uses his right arm for power and his left arm as a rudder.
On his eight-month birthday, he demonstrated the commando crawl for us, while wearing a new outfit (above) that his mom bought him. Here's a QuickTime movie of him in action!
http://www.tcf.ua.edu/Jeremy/Commando.htm