It's a fairly old trick now, but if you use some particular Google queries you can get access to hundreds of unsecured webcams that are used as security cameras.
The query is: inurl:"ViewerFrame?Mode="
There are a few other queries you can use to find the webcams. One of the first places to mention this 'hack' was graffe.com, but it is also mentioned on theregister.co.uk and boingboing.net. Apparently you can also control people's printers with the correct queries. Dodgy stuff indeed!
Here is a site that has collected a whole bunch of these webcams in one place.
Here is a webcam (intentionally public) from the city centre in my home town, Dundee.
Finally here is a pretty good one of an African waterhole, where you can see antelopes, zebra etc.