I've been using WebSite-Watcher for quite a while now, registering through one of the DC Discounts
I like it and use it a great deal. Like Mouser, I have quite a few web pages set up. Many of them are checked daily. If, for example, you wanted to watch the online inventories of camera shops for particular items, you can be alerted when anything new appears. You can set particular keywords, just as in some RSS readers, so you could check if a new version of a program is available by checking for the version number on its web page.
I've only scratched the surface of WSW. One day I might aspire to something advanced, like using WSW to log in to my account at the county library and finding out if any of my reservations are ready to pick up. The account is password-protected, and WSW can do the login automatically. Or, you could use WSW to check low-traffic newsgroups .
At work I use it for competitors and customers web sites. It checks the first time and says "OK;" a week later, or whenever, I run it again, it shows which sites have changed, and what the changes are. They're highlighted to make them obvious. That's a good way to spot new press releases and new products as soon as possible. It keeps the before and after pages, too, so you have them on file until the next time you check.
Perhaps the key point for you is to realise that it works on pages that don't
have RSS feeds, and in fact that seems to be most of the web. I've only just started to look into RSS (with GreatNews) and so far, compared with WSW (which you can also use as an RSS aggregator, though I haven't) I'm not sure I know what the fuss is about
However, RSS is probably better suited to fast-changing and public things like blogs.