To avoid confusion, this list is made up of movies that are underrated OR obscure OR hard to find (or sometimes a combination of any of these three).
I put the more popular/recent titles first to get more views.
So just to clarify with some examples:
"Unbreakable" is underrated as most critics passed it off at the time of it's release but it has since maintained a strong following with over 160,000 votes on imdb.
The Malayalam film "Elippathayam" (Rat-trap) written and directed by Adoor Gopalakrishnan is acclaimed but it is obscure even in it's country of production. It is still available on DVD with subtitles from the UK company Second Run, however, so it isn't hard to find.
Whereas the Turkish comedy "Outrageous Class" is very popular in Turkey and has a high rating on imdb, it's not available legally with English subtitles on home video overseas, making it hard to find.