All priests know (and love) the power of CoH, and Prayer of Healing (PoH) is usually neglected. But it has it's very good uses too, especially with a little bit of exploiting!
What you do is make a macro to switch players to your group. remember that some people are unwise to switch groups with, like melee will loose Battle Shout etc. Keep to casters and healers. one click will switch them to your group, clicking it agian will switch them back. A really nice way is to have this macro switch mouseover ppl to your group, and you can select people really really fast.
Start casting PoH (it's a long cast-time). And move people (either manually, by pre-determined macros or by a mouseover macro) to your group. You can move them to your group right before the heal lands and they will get the heal.
The result? You'll heal up to 4 (5 if you count yourself) ppl every 3 sec that needs it the most. Healing them for several thousand. Also you will never get any gcds!So you can always cast AoE dispell if it's needed really fast (like on felmyst) without having to wait for the gcd to finish.
It's pretty intense playing and requires focus, but the results can be INSANE healing (watch out on threatmeter lol).