Isn't she the cutest?
Custom 60% Bluetooth Keyboard, from teaandtechtime.com, nice for bluetooth uC and shift registers.
ATMega32u4: Scanning a full-size keyboard matrix with two 74hc595 in series, from mehmedbasic.dk, how to interface shift registers and an ATMega32u432u4.
Deskthority wiki pages, lots of awesome resources about PCB design, switches, controller boards, ghosting, etc.
Mechanical Keyboard and where to find them, loads of open source keyboards.
Custom keyboards on reddit, thread with lots of external references.