If I may, I would like to summarize all of the insightful comments above:

When coding in an Apache/mod_perl environment, always always always always always always always always always always always

  use strict;

I was up until 7:00am one morning debugging someone else's code during a nightmare launch of a web application. The behavior of the application was utterly bizarre and confusing, and I acquired a goodly number of grey hairs before I noticed that a junior coder hadn't used strict in one of his modules. Let's just say I was a bit peeved.

It's more of a mantra than a pragma for me: I use strict for everything I write that's over 10 lines of code.