Check out this article from AboutMyPlanet.Com...
The Eco-Friendly Wedding Planner
I guess I should have read this article before I got this far down the road with planning. Wedding's really are a practice in gluttony and superabundance. Why not try and combat that with some eco-friendly practices?
How about a buying some carbon credits to offset your traveling guests?
Carbon Fund has an awesome calculator which allows you to see how many tons of CO2 your guests will be emitting and what you need to do to offset that:
Other ideas include using a caterer that specializes in local & organic food, having invitations made from recyclable or plantable materials or not even having printed invitations - do them all by email! there are eco-friendly materials for dresses, and the list goes on. I'm the first to admit I am not the most eco-friendly but I am getting MUCH better and am going to try and do at least one or two things for the wedding. One - we are definitely going to do a donation for our invite (OK, not necessarily eco-friendly but it is socially conscious) and Two - I am planning to use reusable grocery bags for our out of town guests welcome package - cheap and enviro-friendly)
Here are some other sites and articles for ideas on eco-friendly weddings:
World Wildlife Foundation - Wedding Tips
Saving the Earth, one vow at a time - San Francisco Chronicle