In the 'old' days, Safari was probably the only Internet browser with some decent color management. The problem was that images displayed in Firefox and Internet Explorer looked a bit desaturated and lighter.
Now, in FireFox 3 you have the opportunity of enabling color management. Just set the following configuration option to 'true' (by double clicking) in the FireFox configuration settings (to access the config-part of FireFox, just type about:config in the address bar).
gfx.color_management.enabled
This feature is turned off by default. Restart firefox and be amazed by the colors in your photos on the Internet