Web browsers can affect the way color is viewed by the end user.
Designed for speedy display, they aren't often optimized for image fidelity. Combine that with web designers who, understandably, squash images to their smallest size and you end up with poor image quality on many web sites.
Microsoft's Internet Explorer has supported ColorSync on the Mac since version 4.x.
To tag images (include profiles) that are going to the web, HTML commands are available. See the following links for more information: