A personal selection. I also added some that I haven't seen yet, but of which I heard good things.
Feel free to add yours in the comments.

Great selection.

If you are looking for a gem;
The Giant Gila Monster is a good one. Not so much the monster as the acting and dialog. I really enjoyed the crazy old coot and the mechanic / sherrif's relationship.
Quite entertaining!
You can find it streaming online if you look.

Just out of curiosity, do you not like Alien?

Oh, I do. Not as much as I love Blade Runner, but somehow I forgot to clip Alien. Shame on me. Thanks for reminding.

I haven't heard of the Giant Gila Monster. IMDB rates it at 3/10. Would you say it's underrated, or does it take a special appreciation for monster movies to like this one? Personally, I'm not particularly fond of monster movies nor the horror variants of sci-fi (though Alien is an exception).

Thanks for the input.

Would you say it's underrated, or does it take a special appreciation for monster movies to like this one?

Oh its CHEESE alright but I watched it expecting it to be really bad and I found the acting, characters and dialog very refreshing and loaded with entertainment. The 'Monster' was crap but the tweener parts were fabulous. I wouldn't buy it or even rent it. But if you have a chance to watch it - I say go for it, its entertaining and fun.
The Giant Gila Mononster at http://www.bmovies.com/

At Google video

I clipped it

I need to watch Brazil soon.