For me, these are not very well known:
The Devils Rejects/ House of 1000 Corpses
Fraility
Control (with Ray Liotta)
Torso: Whores with Saws (haha my boyfriend bought me that...)
Desert Saints
Rest Stop: Dead Ahead
The Attendant
The Abomidable Dr. Phibes
HeartStopper
THX 1138
Shark Attack 3
I have Gummo on VHS, the movie that Louis Walsh said didn't exist as he had never heard of it on the X Factor.
I also have:
Swimming With Sharks
Pump Up The Volume
Say Anything
The Beyond
Perdita Durango
The Salton Sea
Pecker
Deconstructing Harry
Hedwig And The Angry Inch
Ghost World
Suspiria
Baby Doll
The Believer
The Company Of Wolves
Funny Games (not the remake)
Adaptation
Brain Dead
Bad Taste
Jesus' Son
Bamboozled
Son Of Sam
Cry Baby
Carnival Of Souls
My Neighbour Totoro
Mi Vida Loca
These are just a few off the top of my head, have to go hunting through the VHS's to remember the full list but I'd say the average movie goer wouldn't have seen most of these films.
I confess that I've not actually watched it yet.
I've read that it's pretty poor but it can't be any worse than "The Beginning of the End" . . . I hope.
Rat - Irish film late 90's, Pete Posthelwaite and Imelda Staunton
Wrongfully Accused on R1, Leslie Nielsen, it's not as good as the Naked Gun trilogy, but brilliant nevertheless.