Online invites certainly have their appeal. They're inexpensive, green, fast, and there's little danger of a guest not receiving your invitation (unlike using the USPS...especially if you live in Chicago, where we were recently honored with "Worst Postal Service in the Nation").
On the other hand, online doesn't feel very special. The romance of opening a card, wondering what it's about, and then seeing some pretty paper doesn't exactly happen at the click of a mouse.
Paperless Post is the exception.
I learned about Paperless Post when an association of which I'm a member started using this lovely service. In the sometimes unsophisticated world of online invitations, Paperless Post brings an air of civility to the computer age. While it's not free (but costs as little as 5¢ depending on the quantity of stamps purchased), it's infinitely less expensive than sending real invitations, and much classier than the usual online options.
Here's how it works:
1) Purchase stamps - you will need one for each person you invite. All accounts start with 25 free stamps.
2) Design an invitation. There are many designs to choose from, and the interface makes it easy to customize.
3) Add guests
4) Track guest responses
See this demonstration to watch Paperless Post in action. It's free to sign up and explore the site! (and if you sign up with this link, yours truly earns some stamps) :)