Found the zoom and full screen features in Firefox 3 very useful, just take following scenario. Figure 1 are before using the Zoom and Fuulscreen mode, in Figure 2 the reading experience are so much better.
If you follow my previous entry, you can now browse Zinio (selected) Magazine free. In default mode the viewing experience are not that good, but after using the zoom mode it's so much better. Just compare the screen yourself.