One of the first plugins, and still arguably the most powerful, bzfscron allows you to run arbitrary /slash commands on a schedule. It supports a very complete crontab parser that closely approximates those found on most modern *nix systems.
With bzfs 2.0.x, limitations in the server API force bzfscron to use an ingenious, but hackish way to deliver its commands. An "observer" called "bzfscron" joins the server. The plugin promotes itself (the pseudo-player) to administrator automatically, so you don't need to worry about permissions. Establishing a TCP connection to one's own thread is very weird and very ugly. However, for the limited purposes of this plugin, it works.
Bzfscron in version 2.0.10 accepts a config file to to specify crontab and observer name.
Bzfscron has been completely redesigned to use a server-side player in BZFlag 2.99 and newer.