Yahoo! BrowserPlus An Excellent Browser Extension

BroswerPlus is an open source technology for web browsers that allows developers to create rich web applications with desktop capabilities. It exposes new functions to JavaScript that allow web applications to have secure access to desktop facilities. Web pages can interact with BrowserPlus through a set of APIs that work in all popular browsers..

Some ways you can use BrowserPlus today to enhance your own site include:

Advanced in-page uploads with multiple file select, mime-type filtering, multiple file or folder drop, and efficient uploads. A drop-in JS Library allows you to quickly add a skinnable advanced uploader to your page without modifying the server logic that accepts the POST.

Desktop notifications unobtrusively deliver updates to your users when their browser is minimized with native "growl style" alerts/toast on your desktop. External frameworks are not required. Integrate native notifications into your site in a couple lines of javascript.

Few Samples:

The BrowserPlus™ Advanced Uploader

http://browserplus.yahoo.com/developer/web/toolbox/upload/

PhotoDrop

http://browserplus.yahoo.com/demos/photodrop/intro

SDK
http://browserplus.yahoo.com/developer/service/sdk/

Developer APIs

http://browserplus.yahoo.com/developer/

I build a small upload solution for one of my client. Working to evolve it more.