I rarely promote websites, but this service is so useful I may be able to stop carrying a thumb drive. It works like NFS, any is simple enough for everybody.
GetDropBox syncs files in a PC folder to the web and to other people's PCs (those who are authorized to share). A small program runs on each PC, or files can be retrieved via a web browser.
This is a simple way to share/sync files in a folder to multiple PCs and is particularly useful for carrying around files to multiple PCs.
From http://www.getdropbox.com/ :
Changes to your files are instantly synced across your computers.
It's seamlessly integrated into your desktop.
All of your stuff is available via the web, so you can get it no matter where you are.
Share the love Invite friends and family to a shared folder for easy collaboration around files.
You can undelete files or restore old versions in a snap.