Yeah, you can play the Wii with just one controller. However, If you're gonna throw one of those crazy Wii bowling parties or ya want your roommate to be able to play with out, more than one if clearly the most practical solution.

Beams money through Bluetooth up to 30 feet away Used as a remote, operates up to 15 feet away
Built-in speaker Rumble Features expansion port for additional input devices, such as the Nunchuk controller The Nunchuk builds on the simplicity of the Wii Remote and goes an extra step to meet the needs of specific types of games. The Nunchuk connects to the Wii Remote at its expansion port and is used in conjunction with the Wii Remote. Along with the analog stick, the motion-sensing Nunchuk also contains two buttons positioned for quick access. Because the Wii Remote and Nunchuk are only relatively dependent on each other, players are free to hold them in whichever hand is most comfortable. Finally, please note that all Nintendo and PS3 consoles are not eligible for returns. All sales on these items are final. (via onlinegiftstore4us.com)