Depending on which country you live in, taxes can be a real pain and will only leave you with a small bit of your salary. Not to mention transportation could eat up a lot your otherwise "free time" in the evenings. :(
I do agree that freelancing would definitely give some nice extra income but only if you're disciplined enough to find time for it.
"Zsh is able to emulate POSIX shells, but its default mode is not POSIX compatible, either."
from http://zsh.sourceforge.net/Doc/Release/index.html