As far as suggestions, I was a little underwhelmed with the 'Example Registry' section. Really didn't show a lot of the features you have available. I would suggest more items in the registry, and maybe a screenshot of the mobile app in action.
Also, without delving into the FAQ there is no easy way to determine the cost of the service. I had no idea that it was free at first, and just assumed you took a cut of online sales, had a processing fee for each purchase, etc. I would definitely put some more info about the associated costs (or lack thereof) more prominently on the main page.
Otherwise, looks sweet! Hope it goes well for you! One cool moneymaking idea here might be using Amazon Associates to get referral $ from amazon items (or let the couple use their own amazon associates account). Not sure if that would work with their TOS but it would be more $ for you...