Build a mineral oil computer aquarium. It cools the system while giving you something to look at.
The setup is quite simple -- with a few cuts to the top brackets on the aquarium, and an acrylic panel cut to provide a flat base for the motherboard to rest on, there isn't much else that had to be done in terms of assembly. If we had to do it again, we'd find a better solution for the power supply -- it is a bit clunky down in the bottom of the case. If you're adventurous, you could always remove the housing from the power supply. There is a real risk of shock if you don't handle it properly, but without the housing, the power supply would look much more at home in a system like this. We also didn't intend to run the system with fans, but once we saw them spinning slowly in the oil, we just couldn't resist keeping them! With the oil, they made no noise at all. In our follow up in a few months, we'll let you know if the slow spinning eventually burns out the fans.