This plug-in for Colloquy enables live Wiki links to be shared in chat rooms.
Wikifier also lets you customize the link display text. Using [[User:foobaz|]], you can create a link to the User:foobaz page on Wikipedia that displays as just "foobaz."
Installing Wikifier is a straightforward process: just unzip the file and move it to ~/Library/Application Support/Colloquy/PlugIns/. If that directory doesn't exist, you'll need to create it. Once you've installed the plugin, simply type /reload plugins in Colloquy to get started.
Whether you're a seasoned IRC user or just starting out, Wikifier makes it easy to create and share Wikipedia links without having to switch between applications. Give it a try and see how it can enhance your IRC experience today!