I recently loaded up Minix 3 in Qemu. It isn't exactly user friendly, but it works. From what I understand, it does seem to have some benefits.
I was wondering if there was any way you could validate or invalidate some of the claims regarding the different alternative OSes out there.
I would love to see how Minix, Plan 9, and HURD stack up against each other and against Linux or BSD.
You could time some gcc compilations, and perhaps find a way to test the stability if that's possible.
Would make for some excellent flame wars, and probably drive site traffic for a long time to come.