Not QUITE about actual films, but...

[RCMerchant]

Double bills I seen in the 70's....
.HOMEBODIES and PSYCHIC KILLER
.NIGHT OF THE HAWK and RACE WITH THE DEVIL
.FROGS and DR.PHIBES RISES AGAIN
.NIGHTWATCH (with Elizabeth Taylor!) and the TOWERING INFERNO
.WILLARD and (gasp!) NIGHT OF BLOODY HORROR!
.DRACULA AD 1972 and YOG! MONSTER FROM OUTER SPACE

http://www.youtube.com/watch?v=4G3bY8KtbSI

Yup-with Peter Fonda,Warren Oates,Loretta Swit...and some other chick.

RC ... was RACE WITH THE DEVIL the one that had 2 couples driving around in an RV or something for most of the movie?

[Pacman000]

I wish they still did this...

[The Gravekeeper]

Alas, I was born too late to enjoy the great drive-in flicks. However, there was still a drive-in theatre in Moose Jaw, Saskatchewan when I was growing up, so I got to see Jurassic Park, Ghostbusters, and (I think) Twister while we were living there.

I really wish drive-ins would come back in style. It beats waiting in line, buying tickets for everyone in the group (I don't like going to see movies alone, okay?), and then getting into the theatre proper only to find that thanks to everyone wanting a seat between themselves and any possible strangers, you're either going to have to ask people to move over or your group is going to have to split up.