I picked up an S-Controller to USB-A adapter from
Mods4Less (the cheapest place I could find them at). I got it in the mail today and it's a dream come true. I downloaded the drivers from
redcl0ud's site. The XBCD drivers (and the audio/mem drivers). Despite some incorrect wording in the readme, all analog controls are analog, all digital are digital. The sound through the live headset works great, the controller is easy to calibrate and there are some nice features with those drivers.
Personally, I bought this so I could use my S-Controller for Star Wars Galaxies: Jump to Lightspeed, but frankly, the S-Controller is probably my favorite controller of all time, and I'm sure I'll use it for other games as well.
Before anyone mentions it, yes, it's pretty easy to make one of these cables yourself (and the drivers are a free download). I wanted something that looked nice and was molded to last rather than hacked apart on my own.