Fel Armor affects healing done by 20%, and that includes Healthstones/healing trinkets.
If you're fighting a warlock in arena, make sure to spellsteal him. It'll be like applying a MS to him... sort of.
Also, it helps you as well. Ever had a <5k healthstone crit? :]
http://img219.imageshack.us/img219/1150/hsup6.jpg
It also works well with Talisman of Horde/Alliance.
Again, not an exploit, but I hope this tip helps some of you.
P.S. Apply Detect Magic to a target before you sheep him, so the Pally will have to Dispel one more magical effect before taking off Polymorph!