The SlingBox is basically a device to capture a feed from your cable or satellite service and rebroadcast it to an internet connection. You then call up the connection on your computer and can watch and listen to whatever service it's hooked up to. I got mine at Best Buy, I think they're around $240. It's a one time hit as there is no ongoing subscription fee. It's relatively easy to set up.
I like mine as I have to travel for work quite a bit and it lets me keep in touch with the local news.
You can go directly to their web site here:
http://us.slingmedia.com/page/home