I ended up spending most of my time productively, writing code. However, I did spend a significant amount of time in IRC channels, Lobste.rs, /r/netsec, /r/python, /r/crypto, and /r/malware.
(Only on waning gibbous moons.)
I can't think of any other tool which solves the same problem as IRC, so it seems doubtful that IRC will be joining the ranks of the dearly departed anytime soon.
Whatever you're interested in, there's most likely a channel on some server which focuses on it, whether it's math, literature, jailbreaks, python programmming, security, torrenting, etc. Here's a list of EFnet channels[0].