It depends WHERE it snapped off.
If it snapped where the USB connector attach to the body of the stick, it's possible, but realy NOT prety.
You"ll need the following material:
4 peices of small electric whire.
some soldering and a small soldering iron.
You need to crack open the casing of the stick.
Depending on exactly where it broke, it's possible that you could need to remove the metal around the USB connector.
Once it's done, you only need to weld a short lenght of whire between the 4 metal connectors on the plug and the 4 points where they connected with the circuit.
The whires must never cross each other.
This is a link that will show you the final result:
http://thereifixedit.failblog.org/2011/04/04/white-trash-repairs-flash-drive-fix-it/
It won't work if the circuit board itself is broken.
Electro, August 2011