If not, you should be. It's a fantastic way to make your use of the web more efficient.
There are lots of websites that I look at on a regular basis (insert your own joke here!). A year ago, I used to check each of them maybe every day, or every week, or every month, depending on how important it was to me or how much time I had. If I forgot to check one of "my" sites then I'd miss any new content.
RSS (which stands for Really Simple Syndication) does the checking for you. A program called a feed reader checks all your favourite websites for updates. The sites have to be set up to use RSS, but many sites are these days - perhaps most of the sites that you'll want to monitor. If the site has an RSS feed, it'll have a little orange icon somewhere on it that you can click on. The feed reader I use is Google Reader, but there are tons of free readers available.
When I start up my web browser (Firefox rather than Internet Explorer, but I'll leave the reasons for that to another article), my homepage is Google Reader. I've told Reader what sites I want it monitor (some accounting/tax sites, along with a tranche of other sites dealing with various other interests). Reader shows me how many unread new articles there are on each of the sites I've told it to monitor, like this:
So, rather than checking the HM Revenue & Customs site periodically for updates to its internal manuals, which I used to do to stay abreast of the guidance its Inspectors were being given on thorny issues, Google Reader now alerts me when something is added to relevant section of the HMRC site. It saves all sorts of time. Initially you go through an enthusiastic burst of use where you add so many sites' feeds that you can't possibly read them all, but once you've pared it back down to the sites you really want (I've got about 50 sites in my list now), it's brilliant. Try it, I guarantee you won't look back.