Recomendations please.

Check out Bay of Blood.

H.G. Lewis movies are fun to watch,too. "Blood Feast", "2000 Maniacs", "The Gore Gore Girls", "The Wizard of Gore", "The Gruesome Twosome",etc.
Also, Cronenberg's "Rabid".
Others:"The Brood","Basket Case","I Drink Your Blood","Motel Hell","Maniac".

Silent Night, Bloody Night (a very weird film. The script is sort of stupid, but the atmosphere is very creepy and suffocating.)
Intruder (Scott Spiegel's only slasher film! Contains some very gory murders all utilizing elements of the supermarket setting. It even has both Bruce Campbell and two of the Raimi brothers in it! I'd highly recommend it, as it's both very creepy and very funny, but never stoops to being a horror-comedy).
Pieces (not what you'd call a good movie, but it's very gory and entertaining. It has one of the most hilariously random scenes ever, and the ending really comes out of nowhere. This one is probably my favorite bad horror movie).
My Bloody Valentine (a pretty suspenseful and creepy slasher which suffers from major censorship. Good news is that a new, possibly uncut DVD is coming out to coincide with the release of the remake).
Nightmare City (another awesome bad movie. However, it has a great foreboding atmosphere, and the energetic zombie attack scenes are surprisingly potent. Too bad the zombies just look like someone took a dump on their face...)
Spider Labyrinth (a crazy Argento/Bava pastiche with shades of Pupi Avati's House With Laughing Windows. It has a cool plot and a great score, but feels a little bland despite all the craziness on hand. Definitely interesting but lacks a soul. Also, the murder scenes are surprisingly dull, except for a knife-to-the-head sequence that has a really sickening sound effect.)
House by the Cemetery (The highlight of this one is a creepy little kid named Bob who was obviously dubbed by an adult trying to sound like a little kid. Despite some of the ineptitude at hand, I actually genuinely like this one, because Fulci definitely knew how to direct a picture.)
Inside (not from the golden age, but this modern French horror film is better than anything Argento has done since 2001's Sleepless. It has a very dreamy atmosphere and a sort of nightmare logic, not unlike Argento, and it rivals Argento with it's brutal and sublimely photographed murders. I can't wait to see what these guys whip up next!)
Demons (Lamberto Bava's best film by far. Visually dazzling and very entertaining, with a great theme by Claudio Simonetti. The real highlight of the film, though, is probably the bad horror movie the characters watch at the theater, which looks like it would've been a fun and creepy gem in its own right. Also, I can't hate any film featuring an appearance by Bob from HBTC!)
Hardware (a pretty cool Sci-Fi/Horror hybrid from the director of Dust Devil. This film and Dust Devil showed great potential from Richard Stanley, so it's a real shame he hasn't done any features since getting fired from Island of Dr. Moreau.)

Suspiria(and about EVERYTHING Argento has done) and The Shining(same thing with Kubrick) aren´t maisntream, but anyways. You should see some Mario Bava stuff. He´s a real genius and was the inspiration for many directors, like Kubrick, Fellini and specially Argento. I highly recommend "Reazione a catena" (without this film, Friday the 13th probably wouldn´t exist or would be very different from what it is) and "I tre volti de paura" for a start.