While there are a few different electric motorcycles on the market, most of them are pretty expensive, so if you want to cut your fuel costs and do it cheaply then the best approach might be something like what Stryker did. On a budget of just $3000, he put together a vehicle that has a 70 mph top speed and with a 10 mile range.
The cool thing is that Stryker documented most of the process on Instructables, so if you want to try to build your own then you can. If you live close to work, then the 10-mile range should be enough, if not, it makes an easy way to get around the neighborhood. [Instructables via Hacked Gadgets]