http://custombrowser.com/

Custom Browser is a fully functional
Web browser that is customizable.
With its unique interface, users can
create toolbar buttons that seamlessly
execute programs on the local hard
disk, network file system, or even
links across the Internet.
Corporations can use the flexibility
and scalabilty of Custom Browser
technology to restrict Internet access
to designated sites across the entire
corporate network.

Minimum requirements:
Windows 95, Internet Explorer 4.0