PostgreSQL and regular expressions?

Hi everyone,

Is there a way to use a function like grep() against a PG database (or
any database?)
What's supposed to happen is that someone would type in a regular
expression into a control where it would (hopefully) be matched
against the values in an attribute column.

Does anyone have any ideas? If Postgresql doesn't support something
like this, is there a way to process the data stored in a database at
a lower level than at an attribute level?

Cheers,
Robin.