Despite its name, "Really Simple Syndication" aka RSS seems to baffle many folks.
My explanation is to think of it as the blog version of creating your own personal online news service.
Instead of being just limited to traditional media outlets, you can check out new stuff that your favorite bloggers have written.
As I was checking out my Google Reader this morning, I came across this post from Nancy White at Full Circle Online Interaction Blog featuring a video by Lee and Sachi at CommonCraft --the video is getting rave reviews for explaining What and How to use RSS.