Are you out of tune? Do you want to be? Either way, Pitch Shifter uses grain delay to bring the pitch where you want it to be. Or at least somewhere else from where it already is.
The Pitch Shifter will adjust the pitch of the input signal up or down:
Pitch Shifter shines on it's own, but it was primarily created to power up the different "Snapin Hosts" Kilohearts offer. These are bigger effects units that utilize all the available snapins and give you a really fun and creative workflow for combining them in any way you can think of. So have a look at Snap Heap and Multipass right now.
Pitch Shifter is also available as a Rack Extension for Reason over at the Propellerhead shop.