Really Simple Syndication is a web feed format that, similar to a normal webpage starts with "http://" but is an xml file (i.e. usually ends in ".xml"). By subscribing to a website's RSS feed (via an RSS reader like Bloglines or Google Reader), you don't have to be constantly going to your favourite sites checking for new content. Instead the reader checks the feed for you and when it finds new content, it presents it to you. There are also certain benefits - the content (which is presumably what you're interested in) is all that's presented to you. So the extraneous images, strange font colours, sidebars etc are got rid of.
So this gives me a chance to plug the Nimisis.com RSS feed. (I might add feeds to each of the Wii in stock alert services too...) I must confess that I haven't used RSS feeds myself until very recently... I guess a combination of being quite impressed by the ease of use of Bloglines and Google Reader - then being pleasantly surprised at the amount of time I save when surfing has turned that around! So, if that sounds like you too, check it out!