FSP have just released their new Dagger family of SFX PSUs with two models, a $100 500W and a $110 600W. Both of these PSUs feature single 12V rails and are rated 80 Plus Gold, the internals are based off of server quality PCBs and offer DC to DC power.
They ship with a removable backplate to allow them to be used in full sized builds as well, with the small size of the PSU leaving more space in your case for cooling solutions and air flow. The PSU itself is cooled by an 80mm fan, about as large as you can fit in the 125×63.5×110 mm shell.
The Dagger is fully modular, with flat cables to make cable management even easier in a small case. The PSU ships with two PCIe 6+2 power connectors, five SATA, two molex and a floppy plug in addition to the motherboard power cables. You can check out the video below, or click through to read the full PR from FSP.