I have one big weakness (ok, one that I'm thinking of right now) in my quest to be a more environmentally friendly person--I love me some pretty paper goods.
I'm perfectly aware that you can email invitations and Christmas cards and announcements, but I avoid it for all but the most casual things. Because I get a little happy rush out of getting and sending real mail. And I adore picking out nicely designed stationary products, arranging little "photo shoots" to get a nice picture, and putting it all together to mail out--complete with real stamps and all.
At the same time, I'm also a complete cheapskate about it. Like, the almost two bucks a card some of the bigger photo websites charge? For a card that looks exactly like everyone else's? No way.
First, Etsy. For about $15 a per design, there are hundreds of cards to choose from. I've had good luck searching for whatever kind of card it is I'm wanting and "template". (E.g. Here's what came up when I searched for "Birth Announcement Template".) Look for the ones where you send the designer a picture, and they send you back a file with your completed card. I've used Ink Obsession Designs (see above) and Paperamma, and have been pleased with both.
Then, if you have a little time and a decent printer, go get yourself some nice card stock and print away.
If you're lacking either of those--and I confess, most of the time I am--log on to Mpix and have them print your cards for you. I like the postcards (under "press products"), which are under or right at $1 a card, including the shipping and envelopes.
(Disclaimer: My Nice Brother-In-Law works for this company. We like him a lot, but that's not why I use them. Literally everything I've ordered, from postcards to larger prints, has been fabulous. The prices are nice too, and the shipping always seems super fast.)
Last step? Admire your pretty, pretty cards, stick 'em in some envelopes, and broadcast your good news to the world!