Develooper: Real World Performance Tuning for mod_perl
   Slideshow of a talk on several techniques of speeding up mod_perl.
   http://develooper.com/modperl/

The Apache/Perl Module List
   List of all the Apache::* Modules that are used with mod_perl
   http://perl.apache.org/src/apache-modlist.html

mod_perl Quick Reference Guide
   Downloadable PDF and postscript files of this handy reference of mod_perl functions, classes and directives.
   http://old.refcards.com/refcards/mod_perl/