Distributed apps and the browser

Wondering what the possibilities of exploiting the browser are to execute distributed applications, hopefully extending around http://des.codeplex.com Would be cool if browser users could voluntarily share their machines computing power for distributed application needs.

Why browser ? Simply because that is the most used app in an internet connected environment.

 Possibilities :

 1.) Javascript based apps - exploiting the underlying machine structures for threading, figuring out idle time might not be really feasible though AJAX could provide some capabilities.

 2.) HTML5 - a bit more promising, but how do you make sure the application lives outside the browsing session/page as you would want the processing to continue even after user moves across pages. This is worth a read : http://dev.w3.org/html5/workers/

 3.) Browser plugins/extensions/apps - worth a detailed research. As these components live within the browser app and not necessarily within a browsing page session. With enough security rights set-up, these components could in fact access the entire computing power of the underlying machine. Interesting.

Anyone currently implementing open source solutions around these areas / having thoughts , do ping me please.