Om Mani Padme Hum
Chanting "Om mani padme hum", sometimes written as "Om mani peme hung", is a powerful mantra in Tibetan Buddhism that evokes the Buddha of Compassion, known as Chenrezig in Tibetan and Avalokitesvara in Sanskrit. This popular mantra is chanted by many people around the world, myself included.
The literal translation "Om mani padme hum" is Jewel in the Lotus of the Heart, sometimes written Hail the jewel in the lotus. Neither even hints at the powerful effect this mantra has. I use this mantra daily and can humbly attest to its positive effects. (I'm a nice guy cuz of it!)
This page, also about Om mani padme hum, has more detail and other photos. It's worth a look.
Om mani padme hum is sometimes recited 3 or 7 times, or else it's repeated countless times. Not only is Om mani padme hum is one of the most common mantras found in Tibetan prayer wheels. It is also carved in stones found throughout Tibet and India.

Here's what His Holiness the Dalai Lama says about Om mani padme hum. This is another piece from Foundation for the Preservation of Mahayana Tradition about it.
You can turn your hard drive into a prayer wheel by right-clicking and downloading one million iterations of Om Mani Padme Hum in this text file. After that, whenever your hard drive spins it will be erasing negative karma. Don't take my word for it, read this if you don't believe me.
