If your fed up installing some Adobe Air applications who do exactly the same thing that a website, you can use a simple Firefox plugin, called Prism (it works on Mac,Pc & Linux) to build your own applications. Basicaly, Prism convert any website in an app. that you can drop in your Finder or Directory.
It use Firefox’s engine to generate a new window, with or without navbar, who can run in background using few ressources. I’m using it for all websites that usually ran all day long in a permanent tab, like Facebook, Google Reader, Google Wave, or RTBF Labs.
Here is a demo with the new Seesmic in-Browser, released last week. I converted the website in a full desktop application who can almost remplace the « old » Seesmic Desktop (build on Adobe Air). Now, I need Seesmic Team to implement the same features on his web-based application than on his Desktop, and my user experience would be perfect.