Webcams make for great security cameras--except when they're not set up securely.
Insecam is a site broadcasting thousands of online-connected webcams all in one place--thousands of webcams from all over the world, actually, so you can get an inside look at strangers' backyards and home offices as well as a map of their locations. The site purports to "show the importance of the security settings," and promises to take down your feed (if it's posted on the site) if you notifiy them.
Insecam is probably violating some privacy laws, but it's also still a good reminder that you should change your webcam's (and router's and every other device's) default username and password. Insecam is able to grab these feeds because more than 73,000 webcam owners have left the defaults (e.g., admin" for the username and password).
The takeaway: Change the defaults for pretty much any internet-connected device you own, unless you do want to end up sharing with the world.