For most of you, this might be old news, but for the rest it is the solution to a problem that seems to be plaguing a lot of artists who post images on the web. I've noticed that some images look very different in different browsers, and some don't. Until last night I had no idea how to control this. So, If you are frustrated with the same problem yourself, read on. If not, then snicker to yourself at my dreadfully delayed technological puberty and be on your way.
All of the message boards I found simply offered the advice "make sure your images are converted to sRGB", which I was already doing with little results. So I decided to try some other things.
Of course, your photoshop file is the image you want everyone else to see:
So then you sRGB it, save at 72 dpi, and upload, only to be greeted by some pale washy colors in firefox. Safari seems to be doing things right, though...
My solution is this:
After you convert to sRGB, click on View>Proof Setup>Monitor RGB:

AHA! That's what shows up online, is it not?
All that's left to do now is adjust the image back to the way you want it...

And "save for web", using any file type you like:

And that seems to solve the problem. Safari and Firefox are finally getting along. There are a few minor differences, but nothing like what we were dealing with before:

I've tried a bunch of things, and this seems to work pretty well. However, it is probably a sketchy, roundabout way to do something that could easily be done another way. If you know a better way to do this, please let me know, since I am only stumbling my way blindly through this incoherent voodoo-babble myself.