I live on IRC. I have been spoiled by a very active Paradox OT forum on Coldfront IRC. I know all of the people on those channels. I want to have something like that on Hubski. My problem is that the existing conversations on Hubski are very focused on things I do not know about or have interest in. I would love to talk more if I knew what to say.
My tendency in other channels is the opposite of kb's: to keep multi-day conversations going when I and others respond to one another when we happen to be on and active conversations occur when we notice the responses are immediate. As for topics, either start your own or ask questions about others' interests. Ain't no way to hold someone's attention than to get them to talk about themselves and their passions.
IRC is appointment viewing for me; I don't like ignoring it when it's open and it tends to curtail my abilities to do other things. As such, it's not really a place I can dwell. If you were to arrange IRC times, I'd make an effort. If it's "IRC's open whenever y'all" I'd be cautious about giving it my time.