Here's where I get my DE from:
http://www.earthworkshealth.com/products.php?gclid=CMWq84ywhqACFRGfnAoduHG9uA
And here is what DE is:
http://en.wikipedia.org/wiki/Diatomaceous_earth
It can really help with the smell and it dries up the poo.  I use it in my coop, as part of the deep litter method.