I'm interested in a challenge building a set with very much parts. I thought of the Unimog U400. But is there a webservice, where the sets are sorted by number of parts?
Brickset has a data mining page which sorts sets by certain factors including new sets, unreleased sets, most minifigures in a set, best/worst price ratio and best British pound to American dollar exchange rates.
The sets with the most pieces can be found here.