Virtual-Hideout has  a review of the Zalman CNPS8000, a powerful cooler that is only 62.5mm tall.  This makes it perfect for HTPCs and other slim cases, but still keep an eye on the sides, it is as wide as most current heatsinks.
“The numbers in the testing section don’t lie: this unit cools fantastically. Zalman has truly made the CNPS8000 so it lives up to their claims regarding cooling capability and noise reduction. If you’re looking for these features in a CPU cooler but are on a budget, the Zalman CNPS8000 may just be for you.”

Here are some more Cases & Cooling reviews from around the web:

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