Kicking users
/kick nick

Go into "lockdown mode"
(only voiced users can speak)
/mode +m
Go back to normal:
/mode -m


To ban users:

ban syntax:
/msg ChanServ AKICK #instructables ADD nick!user@host reason | hidden_info

"Reason" is public, whereas hidden_info is not seen by the users.
It is expected that you put YOUR name & a timestamp in hidden_info.
So, for example
/msg ChanServ AKICK #instructables ADD pikachu spam | zbanks @ 07:37:37 PM 25 May 09

By tweaking "nick!user@host", you can ban by IP rather than nick
Check their whois for a their hostmask, which you can ban by doing:

/msg ChanServ AKICK #instructables ADD *!hostmask reason | hidden_info

Banning Mibbit users is a bit trickier. Look in their whois, but rather
than pull the hostmask, ban by their real name.
(not sure how well this works, tbh)

/mode +d hostmask