Cross-platform desktop application shell
#application
Using the application cache
HTML5 provides an application caching mechanism that lets web-based applications run offline
Sifter
Simple Hosted Bug and Issue Tracking
sparrow
Super simple mail app for Mac that’s built to work with GMail.
CloudApp
Uber-Skitch for music, files, screenshots etc. Looks pretty awesome.
Postbox
Pretty innovative-looking email client for Mac/Windows. Based on Mozilla tech. Includes ability to annotate emails (finally!)