Designed for single click auto-install auto-uninstall customer support applications where you need to see a customers desktop to help them with something but they can't run a normal VNC server (due to lack of knowledge, NAT firewalls, etc) you can use this solution:http://sc.uvnc.com/index.php?section=12
(NOTE: new location for creator tool is http://www.uvnc.com/pchelpware/creator/index.html)
Download location for custom.zip is http://www.uvnc.com/addons/singleclick.html
We've just gotten this working over here and it rocks. What's nice is they give you the tools to pre-configure the thing and turn it into a small stand alone executable that does everything automatically and uninstall itself as soon as the connection is broken. It seems to work like a champ.
In our particular case both Anatoly and the client in question are behind firewalls so we've set up an on-demand VNC proxy that can be run on a Linux box with a public IP address:http://freshmeat.net/projects/vnc-reflector/
VNC reflector supports the reverse connection (where the VNC server connects out to the viewer or in this case the proxy server.). It took a little bit to get working under RedHat 6.1 (buffer overrun problem I haven't tracked down yet - it dumps core. Just recompile with debugging symbols included and it'll stop dumping). I would not recommend leaving this running for extended period of time on a live server for this reason.