Quote Originally Posted by Sam98034
What about this: http://www.onemanga.com/Naruto/449/01/
"He who controls the Rinnegan is a master of all six Pains' (plural) techniques." "Nagato is the 7th Pain..."

I interpreted that as there being 6 previous Pains, and the next one in line inherits all their skills. Did I read this incorrectly?
I believe you did read it incorrectly. I interpreted it as the six bodies that Naruto defeated are the six pains, with the puppetmaster, Nagato, being the 7th pain.