I've read your previous articles and loved them, but I can't remember all the movies you've already used.
Some that I can think of, off the top of my head:
Critters
Hellraiser
Night Breed
Ghoulies
House
Faces of Death (this is a good one, as the box arts were of Reaper-esque characters and didnt quite allude to what the films were actually about)
Grotesque
Tremors
Return of the Living Dead
Stepfather
Silent Night, Deadly Night
Jaws
Night of the Living Dead 1990
Serpent and the Rainbow
Dolls
C.H.U.D.
Night of the Creeps (good news, youre date is here..bad news is, theyre dead! CLASSIC!)
Shocker
I could go on and on, but instead I'll reference you to a couple of sites that focus on reviewing B-Movies and tons of them are Horror films. Alot of the reviews include original box arts, so you can snag pics and get brief synopsis of the movies at the same time. Good Luck, and I look forward to reading your article.
100 misspent hours is probably one of your better bets, but there is goodness to be found on all these sites:
http://www.1000misspenthours.com/http://twtd.bluemountains.net.au/Rick/liz.htm (And You Call Yourself a Scientist!)
http://www.braineater.com/http://www.stomptokyo.com/