Perlcheat
Perl 5 Cheat Sheet.

Perlstyle
Perl style guide.

CPAN Perl Modules
Search interface to the collection of Perl modules on CPAN.

Perl References
Tutorial that covers Perl references. References in Perl allow users to interact with complicated data structures like multidimensional arrays and nested hashes.

Perl Data Structures
Tutorial that covers using Perl with complex data structures.

Perl Objects
Tutorial that introduces the concept of objects in Perl.

OOP in Perl
Tutorial on object-oriented programming in Perl.

BioPerl Resources

Bioperl.org
The Bioperl Project is an international association of developers of open source Perl tools for bioinformatics, genomics and life science research.

BioPerl - BioPerl Tutorial
An overview of Bioperl, it includes snippets of code and text from various Bioperl documents including module documentation, example scripts and "t" test scripts.

BioPerl talks by Jason Stajich

BioPerl tutorials by Jason Stajich