Mozilla Firefox
Mozilla Firefox, the multiplatform opensource web browser, has been updated to version 3.5. As at May 2009, it has a share of 22.51% of web browser’s usage.
Notable enhancements include:
HTML 5 audio and video enhancement
Private browsing mode [ History and cookies will not be saved ]
Location-aware browsing
Faster Javascript performance
Faster page rendering
Complete release notes here
Download for your operating system here.
A great third party guide is here on how to use Firefox productively.