OK, I thought the computer background thing with the repeating picture was cool, but it turns out there's some people on the internet who totally put me to shame.
I also thought I had a lot of time on my hands.
What you do is take a picture of what's behind your computer screen - cords, a wall, whatever - then crop it so that it exactly matches your screen. You have to be very precise and the effect only works from one angle, but the result can be really neat looking. So of course I had to try my own.
It's not as good, but hey, I've got other things to do.
Anyway, there's a whole bunch of these on the internet. Some of them are truly amazing.