"Listen to city walking tours on your mobile phone," suggests Jennifer Miller of Walnut Creek, Calif. "Visit www.talkingstreet.com for tours in cities such as Boston and New York."

"In Costa Rica, we used our phone to record howler monkeys," write Diana and Rick Chimenti of Livermore, Calif.

"At amusement parks, mobile phones let families with kids of different ages split up," says Jill DeGrange of Salinas, Calif.

"Use your camera phone to take and send pictures," writes Jaclyn Biada of Palo Alto, Calif. "And then ask your friends to guess where you are."

"I use What-Happened.com to broadcast videos, sound, and pictures to my friends," says Susan Hull of Pacifica, Calif.