Sean Guilette: Pi is about a mathematician who's going insane trying to figure out the connection between number sequences and the stock market and Jewish mysticism. Not foreign but definitely cult.
He's definitely the lead actor (and co-writer) in Pi, but Darren Aronofsky was the director/writer. I enjoyed Pi quite a bit and caused me to have high expectations for Requiem for a Dream. I ended up despising the latter quite a bit. It used the same tricks as Pi, but not to good effect. The final "horrific" scene which intercut the fates of the protagonists' drug addictions was nothing close to effecting or disturbing, just funny. A group of naked middle aged guys chanting "Ass to Ass" is sadly funny; did not create the effect intended. I highly recommend Pi. On a side note: I think the score was very effective in Pi, but a Masada/Naked City hybrid courtesy of Mr. Zorn would have been cool, too. Zach