Today I bumped in to one of those apps you always knew should be easy and should have: Fluid. This application wraps up a web site and makes an application icon you can click on to start.
All you have to do is fill in a form and out pops an application complete with an icon. Fluid (http://fluidapp.com) literally makes it easy to make web applications into first class members of your application ecosystem.

So far I have observed a few minor glitches related to remembering passwords, favicons and cookies but these may be resolved by the licensed version - just waiting for the licence key to arrive.