Noctua makes excellent coolers. I have two of their CPU coolers in my dual xeon ESXI box. Their fans are pretty quiet too. I've also had good luck with Nexus fans. Check out frozencpu.com or enpcnoise.com. They have a great selection of coolers and fans.
Noctua,good fan check,overpriced check!
The dirtyferret has some good fans listed.
I'll add Thermalright into the mix,half the price of Noctua and better imo.