I'm not seeing the documentation included with Perl, accessed via command-line. I find the following quite handy:
displays the listing of docs and describes Perl
perldoc -f open
displays the documentation for the "open" function
perldoc -q larry
displays the topics from the FAQs which contain the word "larry"
This stuff is available anywhere you have Perl (if the docs have been installed, some admins are odd), which is handy when you're coding in the coffee shop (without wifi) and can't get to the Monastery.
Perl programming and scheduling in the corporate world,
"Uhh ... that'll take me three weeks, broken down as follows: 1 day for coding, the rest for meetings to explain why I only need 1 day for coding."