GeekShed maintains a list of words which will be censored when chmode +G is set and also a spamfilter of URLs or phrases that are blocked network wide. You can block or censor certain phrases in your own channel regardless of whether or not you have chmode +G set. To do this, you can use the extended ban type ~T. The format of this is:
/mode #channel +b ~T::
Action can either be ‘block’ or ‘censor’. ‘block’ will stop any line containing ‘text’ from being sent to users of the channel and ‘censor’ will replace the banned phrase with ‘<censored>’. Text can also be a wildcard string (i.e. * matches anything). For example, sugar* would match ‘sugar’, ‘sugarpuffs’, ‘sugarstuff’, etc. Example usages of this command are:
/mode #channel +b ~T:block:sugar
The result of this is:
(20:26:15) sugar #foo Message blocked due to a text ban (#foo)
/mode #channel +b ~T:censor:sugar*
The result of this is:
(20:27:31) I love <censored>
Because of the way IRC works, as with chmode +G, the person saying the censored word will not see it as censored on their client however every other channel user will.

If you have any questions, come see us in #help.