Meet the Radica Kneeboard: a hybrid board that provides you with a combined experience of waterskiing and wakeboarding. You will be able to pull off spin tricks, edge & carve, and do a whole lot more on the water. Its beveled edge helps the board sit low in the water and facilitates quick edge-to-edge moves. The board also has a padded, adjustable knee strap.
The O’Brien Radica Kneeboard has something for beginner to intermediate riders. The above video shows it in action. You can get it for under $120.