You said best so I'll tell you what I think is the best. There was a long thread about the NB47J and someone posted a picture of a 40mm Coolermaster fan that he put on the side of the Zalman. Anyway, he took that fan from a Coolermaster northbridge chipset cooler. I plan on ordering one myself when newegg comes to Canada very soon (don't know exact date, but I'll be ordering some single device Vantec cables as well).
I thought of placing it by getting some long screws and putting it righ on it instead of beside it. If it works, maybe I'll post a picture so everyone can see.
I'd like to say too that I cannot monitor the chipset temperature but I can see the motherboard temperature. And when I put my fans on max, it takes down the mobo temperature 7'C or 8'C. I think having a case fan on the side helps.