I'm experiencing some unusual difficulty looking for a manufacturer part number for the connector shown here:
.. which is found on computer fan cable extensions. There are 3-pin versions and 4-pin versions that use a polarization rib (power, tachometer, PWM control): http://www.formfactors.org/developer/specs/REV1_2_Public.pdf
It's everywhere on the web in already-assembled cables but I can't find anything regarding the connector itself using the regular search tools (digikey/mouser/farnell/google)...
The best "reference" I could find is