Not only does David Troy know what you're doing - he also knows where.

The CEO of Arnold-based telecommunication consultant VoxPop, Mr. Troy is the man behind some of the most popular aspects of Twitter, the latest global cyber fad.

For those tired of endlessly rearranging their MySpace friends list, Twitter.com offers a new glimpse into the world by asking a simple question: What are you doing?

Like an instant message broadcast to the world, Twitter lets participants send succinct messages to friends or just share their thoughts.

And it's becoming one of the fastest-growing Internet phenomena since its debut in...