Map-Themed Moving Announcement Card
Just thought this was a nifty idea (though one day I hope to move). But the suggestion was made to make an envelope with a blueprint of your house. I think a blueprint or a map would make a cool envelope. Martha also suggests return address labels with your new address. Pretty cute.
Paper Cuts House - Housewarming Invitation Template (Free) | Greetings Island
Free Printable Paper Cuts, cute invitations for any occasion. I used this site (and this particular invite) for our open house party. Super easy to make, and printed on card stock it looks fancy enough to feel good about it without wasting money.