In my day job, I work for Perforce Software, and the following are Perforce-related tools I've written

P4Ruby

Ruby interface to the Perforce C++ API. Ruby is a joy for all programmers and P4Ruby is far and away the easiest way to script for Perforce.

P4Ruby Library

A collection of scripts and modules for P4Ruby

P4Perl

Perl interface to the Perforce C++ API. See the P4Perl Home Page

Non-Perforce-Related Software

Portkey

Portkey is an Open Source port-knocking daemon for Linux