profanity-blink is a plugin for the profanity XMPP client to blink an LED on incoming messages. It currently supports the ThinkLight LEDs on ThinkPad laptops as well as the blink(1) USB LED.
Converse.js is an instant messaging client for websites. It provides an entirely browser-based Jabber/XMPP interface, and can connect to any XMPP public server. Converse implementes single and multiuser chats, invitations, service discovery, direct registration, contact lists, roosters and vCard exchange, status changes and messages, typing and state notification, and OTR encryption.