First you have google´s experimentation area: http://labs.google.com/
where you can find applications that might become the superb tools currently offered by google.

Among these, you ´ll see google sets :
http://labs.google.com/sets
that will supply you additional words to the ones you typed . Ít doesn´t work too well anyway.

I entered Nietzche + Parsifal and I ´ve got Picasso´s Harlequines. ??? Any idea what the relation might be?