Yesterday we had a Bratislava Perl Mongers meeting and Roman Fordinal was showing us what Cyclone3 is.
What was interesting besides that that it's mostly written in Perl and XUL and that it is made in Slovakia?
Here is the home page
Even XUL is not for everyone as it requires Firefox to be installed, it looks like it's worth the "trouble". The XUL GUI looks very like native application. Code is running on client side and only data are passing between the server and the client.