Launch a program or open a file from the browser.
I recently had a requirement where I needed to launch a program from a browser window. LaunchinIE allows you to start an appllication Word, Excel or any *.exe file from a Link on a web page.
You can download the LaunchinIE.dll and find full installation and set up instructions at the developers site: http://www.whirlywiryweb.com/q/%2Flaunchinie.asp
NOTE this will only launch a program on the local hard drive, so it's only really of use for Intranet type scenarios.