I've read all the pages on EmacsWiki about it, just to see how far I could customize it.
I must admit that I was not disappointed, even if I expected to be. It's quite a nice software, and once well configured it's more convenient that my old [[http://www.irssi.org][irssi]] setup.
While browsing EmacsWiki, I read an interesting idea about channel scoring/temperature on the [[http://www.emacswiki.org/emacs/ErcChannelTracking#toc9][erc-track]] page. The idea is to see if it's worth jumping to an IRC channel to see what people are talking about.
I sat up and started to dig though ERC source code to find the information I needed about variables and functions.
How does it work? Ha-ha, I was sure you would ask. You're so predictable, dude! Read the following, and you'll know everything you ever wanted to know about it since the moment you read the title of that blog entry.
Which probably turned you on.
First of all, the score of a channel starts at zero. Zero means "seriously, don't bother, nothing is happening here".
Upon each new message arrival, the score is incremented by 1. If a new message contains a keyword, your nickname or is sent by a pal, the score is increased by configurable values, by default between 2 and 20 points, depending on the match type. On the other hand, when a message is send by some fool, the score is decreased by 1 by default.
Obviously, if the score is going negative, you really should not jump to the channel.
Finally, the score is permanently and slowly brought back to 0. By default, the score is decreased by 1 point every 10 seconds.
Overall, reading the score should gives you a good idea of the channel temperature.
I'm still not sure what is the best formula to compute the score, but so far the default values seem quite good. We'll see.