erc-notify.el is a EmacsIrcClient module that allows you to keep track of the online status of certain people.

Notify is not enabled by default. To enable it use M-x customize-variable RET erc-modules.

You get a new /-command, /notify. Use it as follows:

/notify by itself lists the users online which are on your notification list. /notify nick [nick …] toggles that nick. Meaning, if the nick is on the list, it will get removed, otherwise it will be added.

The status of the nicks is checked every erc-notify-interval seconds, 60 by default.

Note that you can also use variable erc-notify-list.