Hmm,
http://www.tamacom.com/tour.html looks interesting. I'll need to look further tomorrow
The best stuff I have handy is Lions' Commentary on UNIX 6th Edition, with Source Code.
I do tend to keep my current systems source around though, makes good reading when I get bored :\
__________________
My
Journal
Thou shalt check the array bounds of all strings (indeed, all arrays), for surely where thou typest ``foo'' someone someday shall type ``supercalifragilisticexpialidocious''.