For some time, I've wanted a portable fan that I could use to cool off my guns. Initially I thought about using it while rifle shooting to cool the chamber/barrel between shots. Now that I'm going to the range two to three times a week with my pistols. And shooting in excess of 100 rounds through each gun I need a way to cool off them off. (Short of dunking them in a bucket of water like they did on the 1911 test.)
Of course I could buy duplicate guns, or at least replacement barrels. A cheaper alternative is to buy a cooling fan. I didn't want some dinky toy-like, personal fan but something a little more substantial and capable of a little more volume. I looked at computer fans (muffin fans) and at various "hobby" fans, nothing jumped out at me. But then I went to Fry's Electronics (not the grocery store---same founder though) and ask to see the USB "toys". You know, things like little Christsmas trees and lava lamps, that plug into and are powered by your computer's USB port.
Looky. Looky, what I found.

So I took it home and plugged it in. It gave a nice amount of airflow. For size comparison here it is next to my 629

Rather than cut off the USB connector and wire it to my own battery pack, I decided to hardwire in an alternative connector. So I turned it over to take the base plate off and BINGO. It had it's own built in battery holder in the base. Takes 4 "AA" batteries. I've taken it to the range twice, now. Run it for an hour each time. When it's not cooling my gun, I set it up to blow cool air at me.
Sorry there's no on-line link to that one, but here's another one they offer on-line. If I can find it at the local store I'll get this one too. I don't think I could find a 6Vdc muffin fan and build my own for $11.
http://www.frys.com/product/5442979?site=sr:SEARCH:MAIN_RSLT_PGOr just Google "USB FAN" and you'll see a lot more alternatives.