Scooter surfboard racks are very similar to bike racks and pretty much work in the same way. Unfortunately, they are not interchangeable. At least, I haven’t found any that are, unless your alter the rack itself. Surfboard racks for your bike, bolt around the seat, while scooter racks actually bolt into the top frame section of the scooter. In other words, bike racks have a vertical clamp, while the scooter surfboard rack is horizontal. This is the only main difference between the two.
The most popular scooter rack by far is the Carver Moped Surfboard rack. This rack bolts down into the back frame just behind the seat. It is a also a little more expensive that the regular bike racks. I haven’t be able to find many other scooter racks that compete with this rack. Most of the ones I have seen on scooters are usually custom made by their owners. If you are in the market for a scooter rack I would suggest trying Craigslist. I have seen some surfboard racks on there for much cheaper than listing price.
Here is a photo of the Carver:
You can also purchase this racks from esurfboardracks.com.