I've never heard of it before...
U3 technology lets you download and launch applications directly from your flash drive. The interface runs like a Windows Start menu, with a Mac OS-like interface (though the U3 drive will only work on Windows). The U3 platform is awesome for those who have to work on various computers: You can download the programs you need to the U3 Launchpad, plug it into any PC running Windows XP or 2000, and run the apps from your U3 drive. When you're done, the U3 programs clean up after themselves, deleting any files or registry traces they left on the host PC.