Have an event to plan or just want to send out a cute thank-you note? There are a ton of great designers out there offering up eco-friendly invitations and cards. Check out a few of my favourites:

Made with aster petals and grass! These handmade cards are made from recycled cotton and each one in unique.
These invitations are bound with waxed linen thread and close with a spread of real Edelweiss. The booklet is entirely treefree! 100% post consumer recycled paper envelope.  The Lokta paper is made by  hand in Nepal from the lokta bush which is a renewable source. The envelopes are also made from 100% post consumer recycled paper in either the USA or Canada.
These adorable cards come with real flower seeds that can be planted! Each card will recycle naturally into the soil as the seedlings grow. 
Made from recycled, elemental chlorine free and well managed forest products. For each card bought, she will plant a tree through American Forests!
Handmade and made of 100% recycled material!  These are adorable, enough said.

You could, of course, take a stab at making your own.  Purchase some eco-friendly supplies like these pens or this handmade paper and get creative!

Check out these websites for more great cards!
Bag Lady Designs
Custom Paper
Great Green Wedding