Installable Distributions

ActivePerl

Perl for Linux, Solaris and Windows

Strawberry Perl

A 100% Open Source CPAN-capable Perl for Windows. Works exactly the same as Perl everywhere else.

IndigoPerl

Perl for Windows, comes with an Apache web server included

MacPerl

Perl for MacOS Classic (MacOS-X is BSD based and should come with Perl installed - otherwise use the BSD version)

Perl ports on CPAN

Perl ports for a wide range of operating systems

Apache for Win32

Apache, Perl, mod_ssl/OpenSSL and more goodies all compiled for Windows.

Source Code

Install

The build instructions for the current version of Perl.

Modules

CPAN

The Comprehensive Perl Archive Network contains basically anything related to Perl but is mainly used as a repository for Perl modules.

Activestate package repositories

CPAN modules packaged by ActiveState. ActiveState's package manager (PPM) is an alternative to cpan. Similar to Linux's rpm, it can be used to distribute pre-compiled binaries of XS modules.

Roth Consulting Perl package repository

CPAN modules in PPM format packaged by Roth Consulting.

Also see Perl Installation for user-submitted tutorials on this subject.