C/C++ programming, assembly language, API interception, reverse engineering, self-modifying code, JIT compilers, MMX and SSE instructions, hardware hacking (meaning, programming the registers), decompilers, emulators, Linux building and tricks, Windows modding, DOS programming (who offers that anymore LOL?). You name it. So long as your intentions are not malicious (doing it to learn about computers, NOT to do illegal acts), you're welcome in this club.
Are you interested? Contact me on AIM if you are.