Textual is a popular, lightweight IRC client for the Mac from Codeaux. Now three-years-old, the app was recently updated to version 3.0. To celebrate these milestones, the developers have dropped the price of Textual to US$3.
The latest version of Textual has a long changelog that includes new commands for encrypted chat and support for new scripts like moto that'll give you easy access to commonly used emoticons. There's also new messaging feature that'll playback up to 100 messages after each restart. You can read the full of list of changes on Codeaux's website.
You can download Textual from the Mac App Store. The $3 sale