If you wanted to hack the Slim stuff and run your own code instead then all you need is the Controller as that actually has a DAC and a headphone socket. Storage is another issue though, as you'd be limited to just the SDHC slot, unless the USB port has master support I guess. I guess the lack of the touch screen would be a killer though.

I do love that this is the ssh login for my remote control though:

login as: root
[email protected]'s password:

This network device is for authorized use only. Unauthorized or improper use
of this system may result in you hearing very bad music. If you do not consent
to these terms, LOG OFF IMMEDIATELY.

Ha, only joking. Now you have logged in feel free to change your root password
using the 'passwd' command. You can safely modify any of the files on this
system. A factory reset (press and hold add on power on) will remove all your
modifications and revert to the installed firmware.

Enjoy!
# uname -a
Linux (none) 2.6.22-P7 #74 Tue May 13 11:40:33 PDT 2008 armv5tejl unknown