Some of the things on my list:
Starting (and keeping up with) a compost
Growing an indoor vegetable and herb garden
Setting up a rainbarrel to collect rainwater (use the collected rain to water my vegetables)
Check-out my amazon.com wishlist for an idea of upcoming projects
Try "Guerilla Gardening": This is a new term for me and I've become completely obsessed with the idea; essentially, you find unused and abandoned areas of land that are going to waste, and plant vegetables or flowers, even though its not technically your property to do so. But come on! What urban planning developer doesn't love a good garden??
Eventually, I'd like to get my own chickens. This probably won't happen until far off in the future. But that won't stop me from trying to convince my friends and family from getting them!
There are other things, but these are top on my list.
Keep in touch to see how it goes!