Programming:
C/C++, STL, Boost, Multithreading, WinAPI, GDI+, OpenGL, TCP/IP, Sockets, Audio/Video processing etc.
Embedded systems:
Design, ARM Cortex Mx, ASM/C/C++, Eth/TCP/IP, VoIP, RTOS, Drivers.
Web:
PHP/MySQL and tech based on this. Linux: Debian, LAMP, system administration, GCC.