The first was the Meditation on the Stages of Decomposition of a Corpse, often conducted in cemeteries. I showed images from a famous medieval Japanese scroll; you can look at them too, here, but be advised they're not for the faint of heart.

The gentler meditation was a brief loving-kindness (metta) meditation posted on Beliefnet, led by Sharon Salzberg (one of the founders of Insight Mediation Society, where I encountered metta meditation last summer). It starts like this:
Take a few deep breaths, relax your body. Feel your energy settle into your body and into the moment. See if certain phrases emerge from your heart that express what you wish most deeply for yourself, not just for today, but in an enduring way. Phrases that are big enough and general enough that you can ultimately wish them for all of life, for all beings everywhere.
Classical phrases are things like, "May I live in safety. May I be happy. May I be healthy. May I live with ease."
and ends, after you have expanded the circle of your concerns from yourself to a friend, a someone in trouble, a co-worker and ultimately to all beings, like this:
May all beings live in safety, be happy, be healthy, live with ease.
All people, all animals, all creatures, all those in existence, near and far, known to us and unknown to us. All beings on the earth, in the air, in the water. Those being born, those dying.
May all beings everywhere live in safety, be happy, be healthy, live with ease.
You feel the energy of this aspiration extending infinitely in front of you, to either side, behind you, above and below. As the heart extends in a boundless way, leaving no one out, may all beings live in safety, be happy, be healthy, live with ease.
If the first kind of meditation shocks you into an awareness of impermanence and the evanesence of "self," the second shows self to be self-transcending if you give it a chance. Ethics isn't the opposite of self-regard but its extension. As one experiences how naturally the metta applies to others one realizes it was never just self-regard in the first place (and not just because there is no self).
I waxed rather purple about it, quite forgetting my academic self...