customizable IRC client
Download from PortableApps.com
HexChat Portable can run from a cloud folder, external drive, or local folder without installing into Windows. It's even better with the PortableApps.com Platform for easy installs and automatic updates.
Hexchat is an IRC client with an easy to use and customizable interface, scriptability, multiple language support, multiple network, auto-connect, join, identity, proxy support, SASL, DCC, and more.