How about a block command either in the SPAM section or the SEARCH section.
The BLOCK command should block all search returns of a user defined PHRASE or IP address. The command should also have a password option so that users can have better control over their own system.
For example:
BLOCK 'FlatPlanet'
Will block all search returns with the phrase 'FlatPlanet' featured anywhere within the return.
OR
BLOCK '192.168.0.1' will block any returns from this IP address.

This will give the user greater control over their search requirements. It also allows the 'family' guy to stop his young kids from searching for things like 'sex, porn' etc...