Add Laast revised date to page

Hello All!

I have a website where I like to write how-to’s. I really like when a website puts what date the article was last updated so I can tell how relevant the article is. I was thinking of doing something like this in the sidebar of my site. Maybe something like this:

—————-
Last Updated:
March 4, 2001
—————-

I have tried to make a php variable on the page, like $UPDATE, and just use a text widget to try echo $UPDATE. That didn’t work and I read on another website that I would have to make it a global variable. I don’t think this would be a good idea for my problem because then I would need a different variable for each page. It would be nice if I could create a variable at the end of the page, and have a text widget display that variable depending on what page it is on.

Any other ideas???