confusing packet data

This is something has been bugging me lately.... Etherape is a Linux tool that graphs packets arriving at your host, and shows paths of connectivity. I captured the graphs, at the URL below, from my Linux laptop connected to a Linksys wifi router that is hooked to a Comcast cable modem. Why is it that I can see packet data from IPs all over the place? http://picasaweb.google.com/jimpop/Public# Any insight is much appreciated. -Jim P.