Ask HN: Ideas to promote gift registry service (complementary to evite)

My startup helps people get gift ideas for their party (wedding, housewarming, etc.) from their friends that they can vote on. All identities remain a secret and it's a fun way to get guests involved in the event.

I have started to email wedding blogs offering free accounts as giveaways, novelty sites, etc. and have received some good feedback. The trickiest part has been explaining the concept and how it works but once people get it they say they would use it for their next party.

How else can I market the service? Ideally, it'd be perfect to tap evite customers so they can include a GiftBait link in their invitation, but I haven't yet approached larger sites like evite about this.

Any recommendations on promoting the site? GiftBait can be found at http://www.giftbait.com