The Windows Phone app which has gone free next as myAppFree app of the day is Foo IRC. This is a full featured IRC client that provides a friendly and simple interface with plenty of features and options for customizability.
So download it now and saves $ 1.49.
Foo IRC Features:
Save servers and channels
Auto-connect on client start-up
DCC Chat and DCC Send
Pin servers to the Start Screen
Powerful scripting support (Auto Actions)
Switch server views by swiping
Color coded nicknames
Channel log playback
Auto-reconnect on disconnections