VoltaLinux is a GNU/Linux distribution based on Slackware and includes pkgsrc package system from NetBSD. Recently this project released 2.0 version of their distro where any system administrator can enjoy the clean design of Slackware and power of *BSD with the availability of more than 5900 ports ready to be installed. Basically VoltaLinux is intended for servers or small/embedded devices as it requires only 12MB of RAM (it was tested).
I found the idea to cross the power of above mentioned systems quite interesting. You can download VoltaLinux 2.0 ISO from here, installation instructions are the same as for Slackware.