downtimed is a program that monitors operating system downtime, uptime, shutdowns, and crashes and records such events. At OS startup it logs information about previous downtime. It then periodically updates a time stamp file on the disk, which is used to determine the approximate time when the system was last up and running. During a graceful system shutdown, it records a time stamp in another file. The downtimes(1) command line tool can be used to inspect records of past downtime.
Zfswatcher is ZFS storage pool monitoring and notification daemon. It periodically inspects the zpool status and sends configurable notifications on status changes such as disk failures. It also controls the disk enclosure LEDs. There is an embedded Web interface for displaying status and logs.
YFi Hotspot Manager is a modern AJAX Web front-end for FreeRADIUS 2.x. It has support for vouchers, permanent users, billing post paid, and pre-paid. Multiple languages are supported. Statistics can be generated. It works with CoovaChilli and Mikrotik. It runs on Ubuntu and CentOS. It has Google Maps integration. Third party systems can be integrated. There is thorough documentation.