Complex search advice?

I want to be able to build complex search and reporting capabilities in
to our PHP5 application. We want to be able to save searches for later
use. We also want to build queries from virtually any field in certain
tables from our PHP app. I hope to do as much within postgresql as
possible. Then I start looking for how to enumerate field names, etc.
Before I spend countless hours on seeing if some of my ideas will work
and coding them, I hoped to receive some guidance here as to where I
should start and possibly what are the elements of something like this?
Will anything in contrib help?

--
Robert