Way back in the dark ages I remember an ad campaign for Wisk laundry detergent - their claim was that they got rid of ring around the collar. Check YouTube for the commercials. Note: I don't know if Wisk actually works.
I use WIsk from time to time and we like it. Whether it really removes ring around the collar, couldn't say.....but we don't have any rings around our collars (probably because we really don't wear shirts with collars. But yeah, we use Wisk. And Tide, too.)