Computer screens don’t look the same. Different manufacturers, types of displays, etc. Printers also don’t print out identically colored things. This is why color management options were created. A means to allow users to fine tune how a computer should interpret color on the display and print out. This information gets trickled down from the OS to individual applications, such as, let’s say Photoshop. At the same time photos can be saved with color management settings, thusly making this whole thing fairly more complex.
What I’m getting to is Firefox, IE and mostly everything else that isn’t Safari, at this point in time doesn’t display many photos at their true color. As an example, if you’re on the Mac load up this photo I have of myself on Flickr in both Firefox 2 and Safari. If your on a PC, load this photo up in whatever browser, and also save locally then open up in something like Photoshop or irfanview. Notice a difference? Firefox and IE default to some whack ass color profile, while Safari and Photoshop are are to display this correctly.
Firefox 3 should offer the option to display things true, but may not be enabled by default. For the moment if you’d like to view photos off of my Flickr stream, try running Safari. I know that sounds stupid, but boy do my photos look better.