A heatsink wouldn't chill the air. The way a keatsink works, is the heat from the processor gets transferred to the heatsink, and it spreads throughout the metal. The cooler air then passes over it and absorbs some of the heat. Really it just spreads the heat out. The more surface area, the more the air can get to it to cool it. So putting a heatsink in front of an intake fan would probably just block the airflow. Because, the metal would most likely be the same temperature as the air outside, so the air would just pass through, but be obstructed a little by the metal.
Also, when a heatsink works the way it's supposed to, it actually makes the air warmer.
But, to answer your question, I really haven't done anything out of the ordinary to hep with cooling. The Tuniq Tower works pretty good.
Looking to reduce temps or reduce noise? Liquid cooling uses fans just like air cooled heatsinks. But with a good pump, the water will dissipate heat faster. I like more passive setups that have lower noise. I looked at a small dell chasis where I work, and was amazed at the copper heatpipe solution with the fan mounted at the back, using a duct to transfer the hot air.