Bitwise is a chat program, which might suit your needs. it has the ability to share out a folder to anybody on your buddie list. I have used it with a friend of mine, and it works well.
you can get it from:
www.bitwisecommunications.com
click on "free bitwise" at the top to get to the non-buisness use portion of the site.
The stuff for sharing out a folder is in the preferences of the program.
This is also a great chat program in itself. not sure if it's in the stable edition, but the latest alpha finally gives me an icon in the KDE "sys tray"(not sure of real name)