io9 has a neat gallery of “geeky” wedding invitations, many of which are also gothy, such as these zombies and this whimsical skeleton.

Several commenters chimed in with their own material, including member glamzuki whose wedding was based on favorite movies. The save-the-date is just splendid:

I particularly like this because it’s altered text on actual movie artwork (although I can’t for the life of me remember the name of the movie this was from). Even if you don’t have the artistic ability–and can’t afford to pay someone who does have the artistic ability–to create completely original artwork, if you’ve got some rudimentary Photoshop skills you can turn existing art into something quite clever.