Http://www.placenoun.com/(keyword)/(width)/(height)/

https://github.com/aaronmerriam/Placenoun

https://github.com/aaronmerriam/jquery-placenoun

There is also a special keyword 'random'

http://www.placenoun.com/random/400/300/

You can also leave off the dimensions to get a random image of that noun.

http://www.placenoun.com/bacon/

Or just get a random picture.

http://www.placenoun.com/random/