This would be implemented as a plugin. I know of a few pages that I would like to "watch", to see when changes happen. I'd like to integrate this with my TWiki page. I view this as a "portal" style feature that doesn't belong in the core code but would be very handy. I know there are some services that will do this for you too.
I'm thinking going a step further and storing the HTML from a "watched" page so that a diff could be generated when something changes.
Some of these URLs should probably be moved to LinkChecker.
http://www.mired.org/webcheck/ - was linbot (based on linkbot)
http://linkchecker.sourceforge.net/http://www.linklint.org/http://people.debian.org/~treacy/urlcheck/ is an example of output from one such effort.
-- GrantBow - 21 Jan 2003