Mention of a "Single-Site Browser" is here. m00nbl00d described how it's possible with Chrome or Chromium using the command line. Here's a way to do that with an existing installation of Firefox. I've used the SimpleBlock add-on for the purpose. It requires creating a text file called SimpleBlock.ini in the user's profile folder. The file will contain a regular expression such as this: Code: R: https?://(?!(My.bank.com|Second.site.com|Third.site.com)) The presence of Second.site.com and Third.site.com (or more) depends on whether other sites are needed for the main site, My.bank.com, to function. If they aren't, the line would simply be: Code: R: https?://(?!(My.bank.com)) Depending on the user, a separate profile with SimpleBlock installed can be made for the purpose. Or, the same profile (with SimpleBlock installed) can be used and SimpleBlock disabled when not required. This method works for me with Firefox 11 (beta).