HN is great. Some IRC channels feel like a nano (pretty small) HN with selected users. There are smart dudes in there talking about tech in general. Since IRC is harder to use/access than a normal website/forum like reddit or HN, it tends to filter in some way. IRC by definition is an open network protocol. Hence there is not a single company or institution behind it. Thus, there are no adds or marketing around it. It is purely word of mouth. Finally, it feels more private because you need to login. Sometimes, people feel more comfortable to write speculations about future in a more private and perishable digital space than a public and persistent one like HN.
I hear about them on the surface level from the links people submit, then I get the nitty-gritty details that matter from the comments here, sometimes /. or reddit.