Using LBX with Plume
In low-bandwidth configurations, it may be interesting to study the use of LBX, a X11 protocol-compressing proxy. In most cases, though, it won't because if you are going to thin clients, you usually plan a fast local network (it can still be interesting for WiFi for example).
More information on the way to set it up is to be found here: The LBX Mini-HOWTO and Using LBX.
On Debian, the LBX-proxy package is lbxproxy.