Gelid Solutions have today announced a nifty little product that has been a long time coming. Their new Silent 5 (50mm Fan) and Silent 6 (60mm Fan) fans feature a variable RPM up to 4000RPM and 3200RPM respectively with a noise output listed as 23-24dBA which is probably for the lower speed settings. The fans both make use of Hydro Dynamic Bearings meaning low operating noise. Both are also powered by a Molex 3 pin meaning the only way you will be able to adjust speeds is courtesy of a voltage based fan controller.
Both these fans would be ideal for motherboard chipset fans, rear IO fans (like on some ASUS boards) and Small Form Factor PC Case fans.
Gelid is setting the retail prices the same for both fans, $5 or €3.90. All fans meet the RoHS and WEEE standards and carry 3 year warranties.