Check this out from Cooljag USA

http://www.cooljagusa.com/miniflash.html

A PC fan that can display messages as its propeller
rotates. You can program the fan with your own custom message with up to 128 characters.  It is available in the following configurations:

80 X 80 X 25 mm 1700RPM 23 CFM
90 X 90X 25 mm 1400 RPM 28 CFM
120 X 120 X 25 mm 1100 RPM 49 CFM