When you connect the USB Flash Drive to either Windows or Mac OS system, they try to copy some files to it. USBDriveFresher is a free tool that prevents such files from being copied and therefore keeps the USB clean. In other words, it is a USB Flash Drive Cleaner.
So which files are we talking about? They are .Spotlight-V100, .Trashes, .fseventsd, thumbs.db, .ds_store, and others. By default these are already added to the cleanup rules along with ._*, which means if it detects any of these files they will be cleared immediately. Rules can be added, modified, and removed.
It sits silently in the system tray and does not take action unless the USB drive is not inserted. From the system tray context menu you can choose to either cleanup a USB drive or cleanup multiple drives. There is also an option to custom clean the USB drive.
If you insert the USB drive into a system running Mac OS X and then insert it in a system running Windows, all files created by Mac will be removed upon insertion of the drive. The same goes for any other OS.
It works on Windows 2000, Windows XP, Windows Vista, and Windows 7. Enjoy!