There's quite a few games that only use the Wiimote.
Warioware would be a good pick. Mario Party 8 would likely work too.
There's also a bunch of rail shooter games (like Ghost Squad) that would work. Medal of Honor: Heroes 2 has a rail shooter mode too in addition to the regular FPS gameplay.
A good idea would be to go to someone like Future Shop or EB Games and just check on the back of the box what games only use the Wiimote. Take a look and see what games interest you and then come here or go to a site like
www.ign.com to see if they're worth buying.