I use Neenah paper for my invitation designs.   Neenah has a neat calculator that shows your environmental savings for the amount of paper you use.  For approximately 250 invitations, I save:

40 LBS of wood, which is equivalent to < 1 trees that supply enough oxygen for < 1 people annually.
59 Gallons of water, which is enough water to for 3 eight minute showers .
40,547 BTUs of energy, which is enough energy to power the average household for < 1 days.
4 LBS of solid waste, which would fill < 1 garbage cans.
12 LBS of emissions, which is the amount of carbon consumed by < 1 tree seedlings grown for 10 years .

Awesome!

http://www.neenahpaper.com/