Tomboy is a wonderful note taking program for Gnome. It has some synchronization features built-in, but not everyone has a server to store their notes for synchronizing between multiple computers.
Enter Dropbox: a service for synchronizing files between computers. It works great in Gnome (Windows and Mac OSX as well).
I use Dropbox for synchronizing my Tomboy notes by telling Tomboy to synchronize to a Local Folder:
My one gripe is that you have to go into a note to synchronize. Someone has filed a bug and submitted a patch, so hopefully it will be fixed soon.