Arla is a free AFS implementation with the goal of making a fully functional client with all capabilities of normal AFS. http://www.stacken.kth.se/projekt/arla/
LiS is a software package that comprises an implementation of SVR4 compatible STREAMS for Linux. It takes the form of a loadable module for the Linux kernel. http://www.gcom.com/home/linux/lis/index.html