There's an Italian one called The Nun and the Devil, which is based on a semi-true account of the convent of San Arcangelo in the 1700s. Let's just say the nuns have a bigtime problem with that pesky vow of celibacy.

One other is called Sex Life in a Convent, which is not real pornographic, but there is one great scene where a nun masturbates with a rosary.

And of course my favorite is still the German film Faust im Heligen Arche. Yes, there is a lot of nun-on-nun fisting, but it's also fun because Germans would know "Faust" either as their word for "fist," or as Satan. Some lovely wordplay there.