A&D is cheap, main ingredient is Lanolin and petroleum base (like in Vasoline). The Lanolin is tops, and really does the trick (heck, it works for chaffing nipples on nursing moms AND diaper rashes), but is expensive if you get the pure stuff. Don't need it anyways, A&D has plenty in it and is really inexpensive for a jar.
I discovered it upon becoming a father...used to use Chamoi Butt'r and liked it, but used A&D one day after a run (chafed thighs) and it was WAY better than Chamois Butt'r.
If you wanna get hardcore put some on your ischials as a preventative! Works like a champ. Works great on nipples for running, too (if you're too hairy for taping, like I am).
It is a miracle substance, for sure.