As of version 1.5, AthenaIRC now has multiple connections support through what are called miniConnection windows.  While AthenaIRC is and will continue to be a free program, this new feature of AthenaIRC is a shareware option.
There is no limit on how many miniConnection windows you can have, but it will only allow one channel per connection until the client is registered.  It's not required, and AthenaIRC will not bug you to register, but please remember that AthenaIRC is only supported by your registrations.  Many bugs and new features can only be corrected and added through your support.

You can purchase an AthenaIRC Registration code from the AthenaIRC website for $10, well below the cost of some other clients.  Point your browser at http://athena.paladinmacs.com/register.html to register.

If you made a donation in the past, email me at chiper@macatawa.org for your free registration code.