MSN did a nice article today about 9 new tech gadgets you can make with the stash of old stuff you probably have laying around. One which fits into the USB category, is this USB fan.
Retro and cool looking, you can put together a nice desk fan with just an old tower or power supply fan along with solder and USB connector.

Other new tech gear from old gadgets include a stone age cell phone tricked into a portable safe. Scanner table where you can display items under the glass cover of the scanner and a USB mouse turned up-side-down and carved out for a plant holder.
Not the most impressive conversion, but a fun article to read on your break or lunch hour.