We currently reside on IRC.Sorcery.Net in channel #btc
The most popular IRC client for Windows is mIRC
For Linux (or most other *nix), or Windows if you’re a cheapskate, Xchat is a decent alternative
On OSX, no one has yet found an even half-decent IRC client. The search continues.
If you use multiple operating systems, and have a spare server lying around, Quassel is quite good
Come say hi!
(this page will become more complex once someone with nothing to do updates it)