I agree with a lot of posts here. I think that true love never dies is a great idea for a theme. Perhaps if you have an attic you could set a recorder up in it with chain sounds or something sounding like it's bumping around up there even if it's just a crawlspace in the ceiling. Have some photos of a couple who were supposed to have lived in the house before and now haunt it is a great idea. I think with your invitations pulling your theme in will be really important and help your guests know what to expect for your party. You could also insert a sheet in with famous movie love couples that are dead or undead.... Think.......... the crow (Eric and Shelly)...... beetlejuice(Adam and Barbara)...............Ghost (Sam and Molly)........Night of the living dead 3 (Curt and Julie) these are just a few examples, but I hope it helps.