FreeSlack is a Free eXpansion Pack for Slackware. The project's primary goals are to document all non-free software in Slackware distribution, and to make it easy for users to maintain a fully free Slackware OS.
Slacky :: Italian Slackware Community
SlackBuild
Slackpkg+
Sbopkg is a command-line and dialog-based tool to synchronize with the SlackBuilds.org (“SBo”) repository, a collection of third-party SlackBuild scripts to build Slackware packages.
SlackPack: Slackware packages
Bluewhite64 - Pure 64bit Linux no new release after 13.0 in 2009.
Multilib
adding Multilib Capability to Slackware on x86_64 Architecture
Linux.com - Intro to Slackware Package Management by mfillpot December 3, 2009.