Fee-Free Weekends at U.S. National Parks

I came across this info at the U.S. National Parks website. There are three weekends this summer where you can enter most national parks free. One has already past, one is this weekend, and then there's another in August. Go to the link I provided and look for parks near you and maybe you can enjoy the parks for yourself.
As a side note...
The website also now has these cool picture archives of the Parks. I've never been to their website before, but there are loads of interesting things.