It all depends on what kind of damage. The most likely problem that happens to USB sticks/drives is that the user pulls them out before Windows flushes the buffer so you end up with partially written files and sometimes a damaged boot sector and/or partition. Of course, it may be physical damage by dropping the USB stick in the loo or something in which case there is no cure!
Anyway, the best tools for the job are:
Smart Partition Recovery
http://www.smartpctools.com/partition_r ... ndex1.html
VirtualLab Data Recovery…
http://www.binarybiz.com/vlab/windows.html
NB: The versions available for free above are DEMO only so they’ll both show you a directory tree of all that’s recoverable but will go no further. It takes between one and three hours for the average HD for the process to complete with the first program being a bit faster.