Here’s one I’m not totally sure about.
The headline Where the $40 million went to (Sunday Times Lifestyle, 15 March 2009) sounds non-standard to me; my preference would have been What the $40 million went to or simply Where the $40 million went.
Perhaps this is because what is an interrogative pronoun and hence typically stands in for a noun, e.g. to school (to + what?).
On the other hand, where is an interrogative adverb; hence to school (= to + what?) is an adverbial that answers a where? question.