On re-inventing the wheel and advice, look at what most people use and understand how it works. My favourite type of thing is CGI::Application and understanding how it works and why it works as a pattern of use. It's not simply about perl and the neat-o things you can do, but workflow as well.
in reply to How do you master Perl?
Look at Log4Perl. It's not a hard program to write. It's great in that it makes programming easy. CGI.pm. You can love or hate the innards, but look at how it solves stuff on the high level.
For every time one wants to reinvent the wheel, look at what you thought of, and what exists. The robustness between original thought and the good existing stuff is what one needs to learn. Generalizing into reusable components is where you should concentrate. Learn between too much and too little. Think outside of the original problem so the next time, you can work faster by using the general solution if applicable.
The real world thing is done to death. Not a lot of new stuff is popping up. If you want to play with really novel or just hard stuff, get your PhD. Play with NP == P (Or not equal :)
Give me strength for today..
I will not talk it away..
Just for a moment..
It will burn through the clouds..
and shine down on me.