Here are mine. Most of them are ranger, but still:
Interupting Attacks can be used for a very effective damage combo:
you can fire off Double shot, savage shot, distracting shot, and punishing shot is almost less than two seconds (granted you start with double shot, also you can add concussion shot if you've got the energy). Total, these attacks do, with a max damage bow (without customization and enchancments) , 13 + 40 + 28 + 21 + 21 damage (123 for the lazy). Stack this little combo with a preparation, kindle arrows especially and watch the damage grow. With Wilderness Survival at 12, +20 damage per arrow strike, 223 can be blasted in less that two seconds.
A more obvious one that more people know about, actually, an idiot could figure it out on his own, but still. Warrior skills Cyclone axe and thousand blades do not have to be used against multiple targets; they can be used as major damage sources for a single target.
Another obvious one that alot of people know. If Greater Conflageration and Winter are in place, all damage on the field is changed to cold damage. Arm your team with Mantra of Cold and

Meledranu's Resiliance is NOT useless! Mo/Rs and R/Mos can stack draw conditions with MR to create a huge source of energy and health. For a Monk, being blinded is well worth +2 Health Regen and +1 Energy Regen.
Illusion of Weakness can be used as a self sacrifice repeatedly with a monk's Unyielding Aura and Vengance in conjunction with a Minon Necromancer to create a large Undead Army before the round even starts.
Thats all for now.