Other than that irssi has a pretty good activity tracker; and combined with a script to allow me to filter out things/channels that I don't want to trigger activity (joins, parts for example, and certain channels I just don't care as much about). On top of this I just have a hotkey bound to "/window goto active" that basically takes you to the windows with the highest activity and the lowest identifier. These ones combined does most of the trick.
But its obvious I can't read and keep active track of 120 channels, often I just briefly glance through things, if someone has lots of activity and/or mentions of me I appear and can keep track. Except that its just manual choice of what channel I want to use at the moment. :)
Not a perfect system, but works for me.
