One of my colleagues, Joe Grez, is starting up this cool new company called PropEle Marine. Which has developed an exciting light weight electric boat motor that's clean and quiet for your kayak, canoe, dinghy, dink, inflatable, pontoon boat, or other craft. It's works kind of like an outboard engine, but it's portable and powered by a modern battery pack. In early tests the performance is impressive (and getting better with every design flip) and it's even been spotted in and around western Washington waters pushing small vessels at their actual design speeds.
Check it out at http://propelemarine.com/