There's one I saw on TV (Discovery Channel) that is built on a Harley frame, goes to 80MPH with a range of 50 miles. I forget what they called it, or the show for that matter. The show was about this group of New Zealanders Traveling around the US. One guy rides 3 electric bikes: An electric bicycle, an electric scooter, and that Harley, all recharged by alternative methods- solar,windmills, and yes,Methane powered generators. His support group follows him in bio-iesel powered vehicles.
Edit: I found it. It's called the Electric Cruiser built by a bio-diesel firm Vogelbilt.
Then there's one I really can't remember the name of. It's a electric dirt bike that for about 20 minutes will seriously compete with 125s!