<< Just an FYI.. there is an entire forum dedicated to this.. Oddly enough it's called "Cases & Cooling". >>
DOH!! He's right though.
Fun question to ask anyway. But without a link (since I don't have any space out there on the Internet) I have the Antec SX830 with all the fan placements filled and a modified side panel. Over the PCI/AGP cards, I have an intake fan mounted and at the top of the side panel, I have an exhaust fan.