A grerat place for 'free' images is Veer. http://www.veer.com
You will need to sign up for a free account to down load 'comp' images.
These are images used to make mock-ups of projects, but for what I use them for the resolution quality isn't an issue.
For example photos, retro trick-or-treat bags and, clip art :
(the bat wallpaper looks great as your PC desktop, choose 'tile')