You need gcc, the c compiler, g++, the c++ compiler, a good editor
, I think libc6-dev.
For java I used the java SDK from sun (which you can download for free), but there is also a GNU-java compiler: gjc or gcj or something.
You may need some development-packages (*-dev).
Python, Ruby and Pearl: I don't know, no experience.
I have probably forgotten something, I'm really not an expert on this, but maybe this will help a bit.