I just found these guys on iTunes (the iTunes store recommended them while I was listening to Opeth), and wow... they are incredible. It seems like sometimes you just have to be hit at the right moment with some music... that's how it was with Tool, and now I'm feeling it for Isis.
^ thats awesome. wouldn't have expected itunes of all places to rec isis to opeth fans, but there's definitely an untapped market for metal fans to get into post-rock/metal etc, so the more the merrier.