I was a goth during the 90's, but personally I'd say that you shouldn't worry too much if something works on a normal punter, it'll probably work on a goth.
Ok that was my boring side, now for my creative one... Anything with tarot/ghost/tigers cards should work well.
If you own these I would recommend using them..
Skewer through tongue (although they can probably all do that due to piercings),
Bullet Catch 22 (themed around the scene from the crow where they swallow the bullets)
Homicide (although I haven't recieved mine yet, it sounds perfect),
Haunted key
Stigmata
Anything from Lebanon Circle (especially 'From Hell')
Pyro perception
Voodoo doll
My little pony (I don't think this is a trick as such, but it'd probably be a good thing to combine with a fire effect)
