Each week I do this. I create a new background image for use in Powerpoint (or another similar presentation program) and I share it here on my blog. These images are free to you - and you can use them however you wish - at home, work, school, church, wherever. I only ask that you share them freely and that you tell others that you found them here.
For those who like to know such things: this week's picture is a close up of a couple of baoding balls.