David Troy is a one-man Twitter mashup factory.
First, he built TwitterMap, a mashup with Google Maps. People that answer Twitter's question What are you doing?" can now also answer the question "Where are you doing it?". You just have to insert a "L:" followed by a place description that Google Maps understands into your tweet. With TwitterMap, you can now easily find twitterati in your neighborhood. For me, that makes "Plazes obsolete, because with Twitter, I'm able to not only see who's near me but also to get in contact with them immediately.
A few minutes ago now, Dave published his newest work: TwitterVision It's a mashup with Google Maps, too. But its purpose is to visualize in real-time what's tweeting. On TwitterVision, every time someone uses Twitter, a bubble pops up at his location displaying his message, together with his icon and Twitter name. And it's simply amazing to watch Twitter in realtime.
Now all I need is a 60" screen to build my own Twitter command center!
TwitterVision: Watch the world communicate. Watch your productivity go down the drain. ;-)