I came across this site that has some good ideas for making homemade face masks using common kitchen ingredients for skin care.

It doesn't get much easier, more pure (be sure to go organic when ever possible, if not give it a good scrub first), or easier on the environment.

Homemade Face Masks

It includes a few links including this one on the the TreeHugger site, be sure to check it out.

Make Your Own Pumpkin Face Mask 

I often like to add a little exfoliating action or ingredients that draw impurities, so I almost always

add a clay to my face masks/scrubs.

Have a look at my Build Your Own Face Mask chart as well as a selection of clays for more ideas.