SQL - not for coding but for building up data repositories and querying them efficiently
Assembler - for taking apart malware if you choose to go this route. This is helpful but not strictly required. It can provide a nice foundation on which many things are built however.
Perl - for hacking up short todos, and an all around useful tool. Also a great stepping stone into PHP.
Python - for interacting with files, dealing with binaries, and much more
VB - again, not strictly required but can be particularly helpful when dealing with Windows.
Adobe Flash - for tearing into you know what
Linux - To understand What Ethical Hackers / Penetration testers do.
Every language which gives you possibility to implement security mechanism is acceptable. When you implement security mechanism, very important issue is to minimize design flows, weaknesses and bugs.
You should really focus on debugging cause humans are the enemy of the web, they let small windows open for 'bad guys' so they can fully exploit the mistake the person made.