Found this neat-o little site from PopCandy.
If you have some free time today, you can make a sand portrait.
Here's my little lame attempt. Sorry I ended up getting my workload just as I started getting the hang of it. ;)
And here are some interesting pieces from their gallery page.
This one has a Van Gogh-esque style to it.
Some one has a lot of time on their hands!
This is one of my favorites