Prayer of Mending is my favorite healing spell. In situations where you have an off-tank, it's fun just watching it ping-pong between the tanks, healing about 7500 health total in just a couple of seconds, and for less than 300 mana! It's also very effective in single-tank encounters if the boss does AE damage to the rest of the group. I love that the charges to PoM fire off without regard to the global cooldown. We (Matt, Rhys, Mike, and I) run Shattered Halls usually without any crowd control, and this one spell makes it a cakewalk.
Optimal use in an off-tank scenario has the main and off-tanks as the only ones with damage when you cast. Cast it on the one that is lowest health, and it will pretty much bounce between the two, with the lowest health one getting 3 charges and the other getting two. In a single tank scenario I don't cast it unless it's an AOE mob, since if only one takes damage it will never bounce again and you only used 1 charge.
A trick to use when the charge bounces to you - fire off a shadow word: death on the boss. It will damage the boss and you (if the boss doesn't die from it), which will cause PoM to bounce to another.
As for binding heal, I've just started using it a bit since the last patch (which reduced its mana cost). I use it anytime I have damage myself and I would have been casting a flash heal on someone else (squishy has aggro).