Did you know that most stock photography sites give away free images? Most will have a "free images" section or "free images of the day."
Being the cheapskate that I am, I download all the free images, all the time and save them in a folder in case I should need them one day. Sort of like a virtual pack rat!
Fotolia has a great collection, which they change daily. Check them out. It's on the bottom of the page under Search Index. Click on "Free Images."
The image seen here is taken from Fotolia's free images.