Here's a list of environmentally friendly options for your wedding (from the Montreal Gazette and "Eco-Chic weddings" by Emily Elizabeth Anderson).
The rings: I myself was shocked to read that a single gold ring can generate up to 20 tonnes of mine waste. Diamonds often originate from areas in Sub-Saharan Africa where the "profits" are used to fund guerrilla military activity.
Opt instead for faux diamonds or recycled gold. Have a two for one and have your engagement ring serve as your wedding band as well.
The gown: A wedding dress can take up to 15 metres of fabric or more. Very often it's made in China using child labor and/or harmful chemicals.
Go local! buy something made in Quebec. Choose a dress that you could possibly alter and wear again. Think organic cotton, hemp, silk or linen - all sustainable, naturally produced fabrics. Consider renting a dress or wearing a recycled one.
The bridal registry: Create a registry to cut down on unwanted gifts you'll never use. Or be totally selfless and ask for charitable donations in lieu of gifts.
The invitations: Consider a simple invitation, using tree free or chlorine free paper. Some companies (The Crane stationary company) offer wedding invitations made of organic cotton. Include a "please recycle" note on the back. Another option which I was introduced to at a friends wedding was paper with seeds embedded in it so that guests could plant the invitations and enjoy the flowers/herbs that grow from them. Or simply send e-vites.
Flowers: Organic (environmentally responsible growing methods, use of recycling and proper waste disposal) flowers are available ask your local florist what they can obtain for your wedding day.
The menu: It is humanly impossible to eat everything at most weddings. It's way too much even if you've been saving room for days and tons of it ends up in the dumpster after the party is over.
Simplify the menu. Have guest return home with leftovers in reusable containers or donate the leftovers to your local food bank.