Sometimes people will set up their webcams, unknowingly allowing all the world complete access to them.
Google will crawl & index these webcams, and they can be found by using a fairly straightforward Google search:
Click this link if you’re lazy: unsecured webcams
These webcams could easily be blocked from Google by including them in your robots.txt file, and it’s usually best practice to put a password on your webcam if you don’t want other people to see it.
There are probably other searches which’ll turn up webcams like this, if you know any, leave a comment below and I’ll add them to this post.
EDIT: I noticed that Boing boing made a similar post in 2005 with the following Google search:
Turns up a few gooduns!