This interesting and rather organic computer modification use tubes of soil as heat sinks in order to draw warmth up to a planter built into the top of the case and accelerate the growth of wheat grass planted there.
At TotalGeekdom they explain the impetus behind the project:
I can’t exactly recall when the idea came to me, but at some point I started wanting to use the heat from a computer as a way to warm the soil and help with germination/growth. I’m about as far from a botanist as it comes, I did some reading online and became pretty interested in the effects of soil temperature on germination/growth. I read different studies and papers from various universities. It was not too long into that process that I became hooked on the idea of using computer heat as a way to control the soil temperature of some sort of living plant life.
The result is a rather clever design that uses acrylic cylinders filled with soil to draw heat up to to the planter in the top of the case. Hit up the link below for a very detailed run down of the project including results from various temperature tests.