ANYTHING by Almódovar. Okay...that's more than ten right there.
Personal faves: Mujeres a bordo de un ataque de nervios and Tacones Lejanos. Átame was really interesting, as was Todo sobre mi mamá. As I said...anything he directed/wrote is worth seeing.
Viridiana by Luis Buñuel
The Carlos Saura trilogy.
El Labyrinto del fauno (okay...not sure I spelled that right...Pan's Labyrinth in English....won the Oscar for Best Foreign Film about two years ago) and Espinazo del diablo, both by Del Torres...Del Torro...can't remember his name.
go into IMDB and look up: Saura, Almodovar, Antonio Banderas...anything that the title is in Spanish is likely to be from Spain, but he did a couple in Mexico, too...Desperado and the sequel. Discount them if you're looking for SPANISH films.
Cross reference any of the major actors in those directors' films, and you'll pretty much have everything that is decent that was made in Spain in the last twenty or thirty years.
There's another one...takes place in a house in Mexico...can't remember the title. The Avenging Angel, I think.
Oh, yeah...El Mar Adentro comes highly recommended, too. I haven't seen that one, yet, but a friend of mine just LOVED it!