CircleMUD is a multi-user dungeon game system (MUD). It is a derivative of DikuMUD Gamma 0.0. A MUD (Multiple User Dimension or Multiple User Dungeon) is a computer program which allows Internet users from around the world to connect to it, create fictional characters for themselves, and then interact with other real users as well as computer-generated entities in a virtual environment.
emlog is a Linux kernel module that makes it easy to access the most recent (and only the most recent) output from a process. It works just like "tail -f" on a log file, except that the storage required never grows. This can be useful in embedded systems where there isn't enough memory or disk space for keeping complete log files, but the most recent debugging messages are sometimes needed.
Framework for User-Space Devices (FUSD) is a Linux framework for proxying device file callbacks into user-space, allowing device files to be implemented by daemons instead of kernel code. Despite being implemented in user-space, FUSD devices can look and act just like any other file under /dev that is implemented by kernel callbacks. A user-space device driver can do many of the things that kernel drivers cannot, such as perform a long running computation, block while waiting for an event, read files from the file system, access the network, talk to a serial port, and more.