Second, you take your sailboard down a huge windtunnel with 10-35mph winds (you'd reach horizontal terminal velocity by sail-running, if not faster by tacking or reaching). Perhaps the sailboarder would have a remote control glove whereby the tighter the glove is squeezed the faster the fan blows the wind.

Third, there are ramps and rails placed in the wind tunnel for those skate experts that can jump, however if you're an amateur you can just swerve around them. Who knows, this might potentially become an olympic sport someday like snowboarding halfpipe or ski-jump or even the louge.