Query By Example
http://pgfoundry.org/projects/qbe
I could just steal my own flavour text from pgfoundry, but why bother?
Briefly: it's a PostgreSQL extension. WHERE and ORDER BY clauses that work by letting you specify a few examples by primary key value, e.g. SELECT field FROM someTable WHERE EXAMPLE KEY foo LIKE ('bar', 'baz', 'quux') NOT LIKE ('plugh', 'xyzzy').
WHERE works. ORDER BY doesn't, yet. With enough Red Bull, maybe tonight it will.