american pshyco did indeed have a weird ending. I also think total recall had a weird ending. I think any movie that ends with you having to decide your own ending, like total recall or existenze or even k-pax are weird endings. Im not saying i dont like those endings i just think it's weird to have an ending where you decide what happens after the whole movie is great.
Spiderman, House of 1000 Corpses, The Virgin Suicides, The Rocky Horror Picture Show, the end of Titanic left room for argument, Gone with the Wind, Anne of Green Gables (cheesy example but one nonetheless), Army of Darkness, Pumpkin, Hearts in Atlantis...
there are more that I have seen...but I can't think of them off the top of my head right now.