So I started Case-modding to my desktop.

After looking on a couple of mod-sites I decided that I could do with some ccfl lights and a window. Later I came up with the idea of making a little stroboscope 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 pulse-width and frequency of the timer I could see my fan like it was standing still... see the little video on this page

How it works:

The timer makes the leds 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 (almost) the same position as the revolution before. Therefore it looks like it is (almost) standing still.
The shaking is caused by the DC motor of the fan (standard DC motor behavior).
So, say the fan is running at 2400 rpm that is 2400 / 60 = 40 rounds per second. If I want the Zalman logo of the fan to be nice and steady, I have to set the frequency to the rounds per second (40)