I have developed a tool for a client that effectively does this using META REFRESH. The page has buttons for the user to select how often he/she wants to see the refresh. Current values are 5 sec, 15 sec, 30 sec and never.

I have a perl script that generates xml data; refreshing the page causes the parsing of the data and conversion to HTML. This allows for colorization of important entries.

HTH, --traveler

BTW, Thanks to XML::Simple, I threw the whole thing together in about 1.5 - 2 hours as a proof of concept. It ran for a year without changes.