Here's a quick list of the movies that I listed on the poll here. You can feel free to add in your own, of course, but if you need a leg up, here's a plot breakdown of the ones I explicitly listed.
Fair warning: If I don't see a clear leader in the polls, I'm going with Santa Claus Conquers the Martians. :) (It inevitably makes the list of Ten Best on various fan websites.)
Santa Claus Conquers the Martians
The Martians have become upset that Martian children have become obsessed with TV shows from Earth that mention a mysterious figure known as Santa Claus. Their solution is to kidnap the jolly old elf and force him to work on Mars.
Laserblast
Alien creatures kill a different alien creature in the desert; the latter leaves a laser gun and its power source to be discovered by a mopey and confused teenager. The power source causes the teenager to mutate, and he goes on a rampage; local police and the FBI give chase. The first aliens get wind of what's going on, kill the teenager, and forget their gun again. Notable because Eddie Deezen plays a bully (you'll know him when you see him; he's horribly typecast and looks like a Revenge of the Nerds regular).
The Unearthly
A mad scientist is obsessed with finding "the 17th gland" that is, apparently, the source of eternal youth. His research subjects are people without families seeking a cure for depression; they tend to become zombies. This is a very short movie, so it's accompanied by two moralizing shorts that are entertaining in themselves ("Posture Pals" and "Appreciating Our Parents").
Time Chasers
The main character, a physicist in faded jeans, creates a time machine out of his airplane and a Commodore 64. Shot with a budget of about twenty-seven dollars, and with the help of a Revolutionary War re-enactment troupe. This may be the only film in the world that features a dystopian future Vermont.
Teenagers from Outer Space
Aliens with a zest for killing and torture plan to colonize Earth as a place to farm their enormous lobsters (excuse me -- "gargons"). Suspiciously-sensitive Derek runs away and falls in with some Earthlings. Truly cheesy '50s sci-fi at its best.
Space Mutiny
A pilot is the only one who can stop a confused mutiny on a spaceship that looks like the original Battlestar Galactica on the outside and a windowed, concrete-floored, brick-walled industrial building on the inside. Notable for a bowling-alley-polisher chase, an improbably well-built pilot, and lots and lots of railings.
