Sorry to bump a thread but here's a good one -

(SPOILER)In the 6th book when Harry and Dumbledore are in the cave harry tries to summon the Horcrux from the middle of the lake by using "Accio Horcrux" and then it tries to escape but then something tries to stop it. However we later find out that the locket in the basin was a fake and wasn't a Horcrux so in theory when he said "Accio Horcrux" it shouldn't have done anything. Unless the 'fake' locket was a Horcrux and Voldemort is still alive!!