DAH Industries is a website my wife, Andrea, and myself used to publicize information about our wedding (DAH: David and Andrea Hayes -- clever right?). We were looking to keeps costs down as well as stream-line the RSVP process.
Guests received a small card in the mail; it gave basic information about the wedding as well as the location of the website. We put all other information on the website: location, hotels, RSVP, menu, and information about us.
Our wedding took place in our backyard about a mile outside of Kearney, Nebraska, but the reception took place at the in town. We had limited parking at our house, so guests were to park at the reception hall and be chauffeured to our house. Since this was a little confusing, and many guests were from out of town, we put maps and interactive directions on the website.
There was a RSVP form was also on the website. Many guests used this feature, saving both us and them time and money.
Finally, we decided to go with a registry at Amazon. We were able to directly link to our Amazon wedding registry list from the website.