Javascript is one of the most popular languages in existence. MUD Client takes advantage of this, allowing scripts to be written for aliases and triggers. Patterns can be regular expressions, and each capture group is handed to your script.
A full range of ANSI colors is supported. Everything from foreground colors, background colors, underlines and even blinking text. Chat is gathered into a messages panel, and an automapper and vitals bars sit beside the game.
Scripts can send system notifications, put a badge on the Dock icon and show values in the menu bar, so your HP is visible at a glance and you can be notified when a creature has been killed.
Scripts can send Windows notifications and put a badge on the taskbar button, so you can see what is waiting at a glance and be notified when a creature has been killed. Each open world gets its own taskbar button and its own badge.