Firefox 1.5 is Out
Firefox 1.5 is out.
A killer feature in this version that I've hardly seen mentioned is SVG support. You might be thinking "yay vectors in a browser" but it's more than that.
SVG is an object model for a graphical image. JavaScript can manipulate this model. This means a whole new level of possibilities for AJAX applications.
Take a look at the SVG Samples page, but especially at SVG Tetris sample, a Tetris game implemented in SVG and JavaScript as a single 13k file.
This opens up a huge number of new avenues for interactive web apps.