Best Way To Dynamically Update A Nav Bar?

What is the best way to update a single file for the navigation bar/menu on a
site, and have that menu update on every page of the site automatically without
using frames or flash?

Right now I update a single flash nav file and I don't have to change each
page individually, but the problem is that search engines can't crawl flash
documents. Would PHP do the trick? How would I go about implementing this?
Thanks.

I've been struggling with the same thing. What I have pretty much settled into
is putting the nav menu into a master template. When I make a change to the
navigation, I only need to change the template... but that will update all
files using that nav menu, so all those files have to be re-uploaded. My site
isn't terribly large, so this method has worked pretty well, though I'm still
looking for better options if any. -Ron