Wolfen is terrible, and I will watch anything involving werewolves, so that's saying something. Here are some werewolf movies you might want to check out:
The Wolfman
Waxwork
Dog Soldiers
Trick R Treat
Silver Bullet (on Youtube in parts starting here)
The Company of Wolves
The Howling
Honorable Mention
Black Sheep
Mulberry Street (found a streaming copy here, but no promises)
Teen Wolf
Oh you haven't seen that episode of Intervention?? You, sir, are in for a treat of the non-dairy whipped topping variety!
Bask in the glory (sorry for the myspace link. I now feel dirty)
Back when I was far too young to watch horror movies, I loved to read the synopses on the backs of videos at the rental store. I've always had a morbid curiosity, and I couldn't wait until I was old enough to actually watch them.
Once I started watching them and developing an interest, I challenged myself to watch all the films on the Bravo's 100 Scariest Movie Moments list, as well as the 30 Even Scarier Movie Moments. At that point it became something of a hobby for me. I've now moved on to this list to fill in the gaps.
My favourite horror movie is Rosemary's Baby, and I'm not sure why. It's very slow moving, but gives you loads to think about so you don't get bored. I really identified with Rosemary's character and couldn't stand the way everyone tried to control her life. Would this be a good one to pick when my choice comes up? I know it's a bit long.
EDIT: The one film that scared the hell out of me more than any other was Haute Tension (High Tension/Switchblade Romance). I watched it in the middle of the day and still had to pause it to catch my breath. Shame about the dreadful ending.
LAST EDIT: What I love about horror movies is that even though I've seen hundreds of them, they still get my heart pumping faster. And they don't even need to be particularly good or original, either. I fall prey to the same traps over and over again. This is why I prefer horror to comedy or drama, because I can only laugh/cry about the same thing so many times.
Thanks for listing them. Isn't there a monstrous mermaid on the beach? And there's a giant clam, IIRC, which must be based on a semi-apocryphal myth about a giant human-killing clam which locks onto the feet of pearl divers, drowning them.
There's a ton of really weird shit in this movie. According to this fan site, a lot of it may have gotten cut or redesigned because of conflicting licenses.
So the Little Shop of Horrors venus flytrap is actually a cloning pod from Invasion of the Body Snatchers.
I highly recommend reading the fan site linked to above. It's a really great read.
That's weird, because the Dark Tower series ties together, in a really bizarre way, almost every book King has ever written. I've only read a couple books in the series, though, but you should really go and read it. It's designed for folks who have read a lot of King. Dark Tower, IMO, places King as one of the top three greatest novelists produced by Western culture. There are people who would literally punch me in the face for saying this, but I welcome their blows.
I haven't read nearly as much King as you have - perhaps only 1/4 of the King library. But my current favorite pick from his prodigious works: 1963. It takes place within the King multi-verse. Part of the thrill in reading it is that you get alternative looks at other parts of King's worlds.
EDIT: I would also recommend - what I consider to be his magnum opus - "On Writing". He sums up how to write.