Scythe S-Flex  
Makes use of "Fluid Dynamic Bearing" technology. The Scythe S-FLEX SFF21D (800rpm @ 12v stock) is the currently the best available choice for those in search of the quietest 120mm axial at standard voltage, with the Nexus now a close second in line.

The Enermax 120mm (like this one) is apparently a Globe relation as well (link1, link2). Most Enermaxes use ball bearings rather than the quieter sleeved the quieter Globes and AcousticFans use (BB equals louder bearing noise). However, what's pulling for these fans is they are available from just about every wide-selection PC vendor and as a resultant have very good name recognition among the general computer savvy. In addition, they are usually bundled with some sort of simple speed controller. I believe this fan would be correctly considered decently quiet. On the quiet side of loud, but on the loud side of quiet. It seems to be pretty popular among "quieter" computing guys who have not yet tasted the fruit of a genuinely quiet fan or are not quite as intent on a truly quiet setup. Spend your money elsewere IMHO. Just including it here so you know where it stands.

The Papst 4412 fans are very nice when undervolted on DC current. They are one of the best quiet 120x25mm fans for restrictive environments. They don't like PWM though. Purely noise wise, they fall in the quiet, but not the most quiet category. The Nexus and Globe (and the more recent additions to this list) options are quieter, but remember, the 4412 is moving a good bit of CFM.  
 
Note: Both the Papsts and the Panaflos seem to be degrading in quality overall. The Panaflos seem to be degrading more so then the Papsts though.

The Yate Loon D12SL-12 is used by 3R systems, the Korean company that builds most of Ahanix's cases. They can also be found in some Fortron power supplies. The Nexus 120mm is a Yate Loon under another label, only the Yate Loon spins faster than the Nexus at 12V and the Nexus's fan blade design possibly has a slighly little more curved leading edge. Unlike the orange Nexus 120mm, the Yate Loon is black. Can be rather difficult to find. Probably the ideal quiet fan as it still retains the ability to crank a bit more CFM on demand but lack the bearing/motor noise of the Globe (assuming the Yate Loon's noise charactersitics is the same as the Nexus 120 in the Nexus's RPM range).