how can i make these vocals sound better?

This Guy Sings Christmas (http://www.thisguysingschristmas.maltesemedia.com/)

Auto-tune plugins.

ROFL - yep, Autotune may be the only answer. And there's that little detail about copyright.

Isn't the off key vocal part of his schtick? Otherwise it's Melodyne or Antares Autotune. Or a new singer, that always works best. ;) john.