The fool says that you can use Wikimedia Commons to find all kinds of pictures or other media that are in the public domain or have fewer copyright restrictions.
I subscribe to the picture of the day which is a great source of visual inspiration. Another source of pictures is the Creative Commons Search engine, where you can find a poisson d’avril by Aldor:
Well, thank you, Harold! Just the other day I was wondering how to set Flickr so it could find CC stuff; that’s where I get 90% of the photos I use on my blog.
There’s also a CC plug-in for the Firefox search toolbar.