Allows you to replicate string table values per-player. The primary use-case for this is to change the server website on the scoreboard (MOTD) per player. Can be used to add an authentication token to the URL itself so the user is already authenticated with their steam when opening it rather than manually logging in.
There is an example for using the metamod interface from CS# in examples/counterstrikesharp/. If you're writing metamod plugins, you probably already know what you're doing ;)
Download release from here. Install in game/csgo/addons/.