I picked up a pair of these units, and I think they are pretty cool. I like what they do for recording drums. They sort of make my little Zoom drum machine sound like it was recorded at Motown or Stax.
Sorry, no sound clips, yet. But here are some pictures (click for bigger).
This is a schematic for a modified version of the Dan Armstrong Orange Squeezer compressor. All of the mods came from a discussion at DIY Stompboxes. The original objective was to optimize the circuit for bass guitar by replacing the half-wave rectifier with a full-wave rectifier, among other mods as noted on the schematic.
I have not built this circuit, myself. But there have been a number of reports at DIY Stompboxes over the years. Reviews are mixed. Some feel that the stock version of the Orange Squeezer is as good as it gets.