So I started Casemodding.

After looking on a couple of mod-sites I desided that I could do with some ccfl lights and a window. Later I came up with the idea of making a little stroboscoop for the CPU-fan.

I took a 555 timer and made this stroboscoop with 5 white LED's and aimed them on my fan

By adjusting the pulsewidth and frequency of the timer I could see my fan as if it was standing still... see the little video on this page

How it works:

The timer makes the led's go on and off with a frequency that is an equivalent of the fan rotation speed.
Each time the led is "on" the logo is in the same position as the revolution before. Therefor it looks like it is (almost) standing still :)
So say your fan is running at 2400 rpm that is 40 rounds per second. The amount of blades on the fan is 7 so the frequency of the strobo-led should be around 40 x 7 = 280. This is on a standard fan. However, if I want the Zalman logo to be nice and steady, I have to set the frequenty to the rounds per second (40)
Obviously, the 280 flashes per second gives a nicer, more continuous view, but I like to see the logo