I recently found the CTRL+F5 shortcut key that you can use in your browser to refresh a page that you are viewing. Below is an explanation of the difference between that and using F5, from the Microsoft Knowledge Base article: http://support.microsoft.com/kb/306832.
Refresh the current Web page F5 or CTRL+R
Refresh the current Web page, even if CTRL+F5
the time stamp for the Web version and
your locally stored version are the same
Basically, CTRL+F5 will force the page and your cache for that page to be reloaded from the web server, while F5 will just refresh the page and display the cached version if one exists.
CTRL+F5 behaves this way for all Internet Explorer versions as well as Firefox, I am not sure about other browsers.