Best back up vocals ever?

What song has the best back up vocals ever?

I say it is Respect by Lady Soul – Arthetha Franklin, “sock it to me, sock it to me, sock it to me.” Second is Hound Dog performed by an A’Cappella group out of Orlando called 4:2:Five, it’s available on itunes and is really worth a listen.

Lurve to Astro Chuck’s answer this question for making me think to ask.