These community-based distributions track the changes in Debian 
Sid (
Unstable) — hence their name. The modifications are limited in scope: the goal is to provide the most recent software and to update drivers for the most recent hardware, while still allowing users to switch back to the official Debian distribution at any time. 
Aptosid was previously known as 
Sidux, and 
Siduction is a more recent fork of Aptosid.