I do most of my work on a desktop computer, but ocassionally I work on my tablet pc. In those instances, it can be a pain to copy files back and forth onto a USB drive. In fact, I'm not very good at it at all - which means I will often have an out of date version of the file somewhere.
FolderShare is a nice solution to this problem. It will sync folders that you select between multiple computers. (It does this using a secure peer-to-peer network, so your files aren't actually stored on a third party computer.) So far, it has worked great for me for little effort.