TrinityOS is a step-by-step, example-driven HOWTO on building a very functional Linux box with strong security in mind. TrinityOS is well known for its strong packet firewall ruleset, Chrooted and Split DNS (v9 and v8), secured Sendmail (8.x), Linux PPTP, Serial consoles and Reverse TELNET, DHCPd, SSHd, UPSes, system performance tuning, the automated TrinityOS-Security implementation scripts, and much more.
ru is a reimplementation of the BSD 'rwhod' and 'ruptime' commands. It doesn't suffer from the performance impact of 'rwhod', scales to hundreds of servers, and supports a variety of platforms. In addition to the features provided by 'ruptime', it supports colorized output, availability reporting, graphing of system load averages using gnuplot, historical storage of system loading, and the grouping of servers.
ConMan is a serial console management program designed to support a large number of console devices and simultaneous users. It supports local serial devices, remote terminal servers (via the telnet protocol), IPMI Serial-Over-LAN (via FreeIPMI), Unix domain sockets, and external processes (e.g., using Expect to control connections over telnet, ssh, or IPMI Serial-Over-LAN). Its features include logging (and optionally timestamping) console device output to file, connecting to consoles in monitor (R/O) or interactive (R/W) mode, allowing clients to share or steal console write privileges, and broadcasting client output to multiple consoles.