Stas Bekman has been a tireless advocate for large-scale applications in Perl and, of course, mod_perl. He went from an occasional asker of questions on the mod_perl list to answering many questions, and had the forethought to write it all down, creating and maintaining the mod_perl guide which quickly grew to over 600 pages. Recently, he made himself available for free talks to Perl Mongers groups during a trip covering North America, Australia, the Middle East and elsewhere.
Eric Cholet may be familiar to you as the technical manager of the YAPC Europe Foundation and as co-author of A Conference Toolkit (ACT), which has been used to administer several European YAPCs. More importantly, though, he works behind the scenes at perl.org, moderating the mailing lists we all use. If you've noticed the absence of spam on a perl.org mailing list, filters help, but Eric catches what falls through.
Andy Lester is one of the prominent voices advocating testing and quality assurance. He has written extensively on the importance of good testing and maintains qa.perl.org. He is also the creator and project leader of Phalanx, which is devoted to improving tests and test coverage of Perl and CPAN modules to maintain quality as development continues. Phalanx encourages interaction between programmers by having groups of developers work together to improve test coverage on the most used CPAN modules.