http://www.ocremix.org/

I just learned about it from a topic in my most frequently visited forum and I have a feeling I might have heard a few pieces before, without knowing they are OCR pieces. And I regret not knowing about it earlier.

Here are some pretty nice pieces, recommended by a forumer and I quite like a few of them too. Like the Metal Gear Solid remix, both linked Chrono Trigger ones, etc.