Only recently was I introduced to the Metta chant. The practice of chanting these words reinforces our aspiration to feel true compassion for all beings — and very specifically, not only the nice ones, but also including the most horrible, awful people we can imagine.
The chant starts with us, ourselves:
Aham avero homi
May I be free from enmity and dangerabyapajjho homi
May I be free from mental sufferinganigha homi
May I be free from physical suffering
Then it continues:
Sabbe satta
May all beingssabbe pana
all breathing thingssabbe bhutta …
all creatures …avera hontu
be free from enmity and dangersabyapajjha hontu
be free from mental sufferinganigha hontu
be free from physical sufferingsukhi – attanam pariharantu
may they take care of themselves happilyDukkha muccantu
May all being be free from sufferingYattha-laddha-sampattito mavigacchantu …
May whatever they have gained not be lost …
You can read the complete chant here, at BuddhaNet.
The Metta Sutra is a different text (read a good English translation here). The teaching is the same:
As a mother would risk her life
to protect her child, her only child,
even so should one cultivate a limitless heart
with regard to all beings.
With good will for the entire cosmos,
cultivate a limitless heart:
Above, below, and all around,
unobstructed, without enmity or hate.
Breathe.

That’s lovely. I’m pretty sure that’s the metta chant I did at a week long meditation retreat over the summer (July/August). I guess there isn’t more than one, right? At the retreat I learned the classical metta phrases (or at least a set of classical phrases) which I find really useful because otherwise I get confused about what to say when. This is what I use:
May you be happy and peaceful of heart and mind
May you be healthy and strong of body
May you be safe and protected from inner and outer harm
May you accept yourself just as you are and live with ease
I find that I like to mentally recite each phrase twice because it helps me remember them.
Like I have said I am here and, for now, this is only to register my presence here. Like I have said this is great blog full of much to be practiced. Deep thanks
_()_ Johan Rosh