Topics:
Web-Security (SQLi, RFI, LFI, XSS, CSRF, ...)
Software Development
Software Analysis (Format Strings, BOF, HOF, ...)
Malware Research (Botnets)
Exploit Development (Overflowing, developing shellcode, etc)
Roboting and Microcontrollers

Langs:
C, C++, Delphi (Pascal), ASM, Python, Perl, Bash, PHP, Ruby ...