How to put your smartphone "on call"

Applications that run on your cell phone put health and wellness aids just a touch away.

Multipurpose gadgets — from the dubious devices hawked on late-night television to reliable standbys like food processors — capture our fancy because they promise to save space, time, and money. The iPhone, Android, and BlackBerry are no exception. Aptly dubbed "smartphones," they don't just make calls — they're also highly portable, powerful computers that can perform a seemingly infinite variety of tasks, thanks to operating systems that run programs called applications, or "apps."