Usage: WATCH [ADD|DEL|LIST|WIPE] [<nick|room>]

This command will have NickServ manage your Watch list. A watch list is similar to a notify list or a buddy list. It will inform you when nicks you specify are in use. You can add rooms to your watch list and you will be inf ormed when the room empties or reforms. You do not need the person's approval to add them to your watch list.

ADD - Add a user or room to your watch list.
DEL - Delete a user or room from your watch list.
LIST - List the entries in the watch list.
WIPE - Remove all entries from the watch list.

/msg NickServ watch add Mark
/msg NickServ watch add #ConferenceRoom
/msg NickServ watch del Mark
/msg NickServ watch list

Like the buddy command you can use this for people or rooms that you often interact with. You should not add someone to both your buddy and watch list as that would notify you twice each time the person appears or disappears.

Other related commands:
/msg nickserv help buddy
/msg nickserv help set authorize
/msg nickserv help auth