Most electric bikes and still bicycles. It's a growing market segment with new advances in technology and design. Big manufacturers are building them, even bigger makers, like Yamaha, are showing off some really advanced prototypes.
There are kits people can buy to add on to existing bicycles. There are numerous home made conservsions and there are specifically designed eBikes for sale almost everywhere these days.
I personally think that this forum deserves its own section for eBikes. There are specific discussions that relate only to eBikes (electrical, motors, controllers etc.) that go beyond the bike discussion that this excellent forum already covers.
There's a growing population of eBikers just looking for a forum to discuss and a large site like Bikeforums.net would seem like the perfect place to have one.