This week's Pick of the Week on Mac OS X hints, is JollysFastVNC. This is an amazingly fast VNC client. It is significantly faster that Chicken of the VNC. The developer has posted a video showing the speed.
It worked great for me, when connected to my Mac mini running OSXVnc VNC server. It looks like it currently doesn't support the Tight encoding. But, event without that it was completely useable when connecting to the Mac mini over the internet.