Want to track changes on a site that doesn't use RSS? TrackEngine will send you email notifications whenever a specified site changes.
Once you've registered, using the service is pretty straightforward: it incorporates a 'Track me!' button which you can add to your toolbar to monitor selected sites (you can also add sites manually, if, like me, you're not a toolbar fan).
You can alter the frequency sites are monitored (daily is the default), or only ask for updates when specific words are added -- useful if, for example, you're tracking gig announcements from a favoured artist. Indeed, there's a plethora of customisation options, right down to the colouring of update emails, in the service's Expert mode. TrackEngine is a free service, requires registration. Thanks Ian!