In the vein of musicals, Sweeney Todd: The Demon Barber of Fleet Street straddles the line between black comedy, straight-up horror and tragedy, and is for my money the greatest American musical of the last forty years. Burton's version is fantastic, and with the exception of Helena Bonham Carter everyone from Depp to Rickman to Baron Cohen sings beautifully well. Listening to the OST right now, in fact.

She's all right. Really, it's less that her voice isn't up to it (though IMO she's far too weak and breathy) and more that she's trying to step into shoes previously filled by Angela Lansbury and Patti LuPone, and of course she's going to lose that contest.

Parents, Randy Quaid movie from the eighties.  I watched this one at a very young age and never went back because it was so unsettling and confusing to me at the time, but I think it's a horror comedy.  Ugh...weird.

The original Toolbox Murders is good retro slasher trash, my friends and I would laugh our ass off during the bath tub scene.

Caught the french flick Inside recently, really solid gore effects and horrible baby cgi.

Deadgirl is a really solid alt-horror movie, great fx, solid soundtrack and ultimately a pretty sweet story.  Different.
P.s. There is penetration to an oozing wound. 

Others that probably have been seen by all, but worth checking out in case you missed em': Slither, Tucker and Dale vs. Evil, Return of the Living Dead, Drag Me To Hell, and two franchise documentaries that are better than almost all entries in the series; Never Sleep Again: Nightmare on Elm Street doc and Crystal Lake Memories: Friday the 13th doc, both excellent.