The Schumann Resonance is the name of the resonance frequency between the Earth's crust and the ionosphere. Read a full article on it here: www.oulu.fi/~spaceweb/te...schumann.html
The primary (strongest) Schumann frequency is 7.83 Hz. Others include: 14, 20, 26, 33, 39, and 45 Hz
The primary frequency corresponds to an Alpha brainwave. Alpha waves correspond to meditative trances or to the dream state. The other Schumann frequencies all correspond to Beta brainwaves. Beta waves correspond to "ordinary waking consciousness."
The brainwave exhibited by "energy healers" when we do our thing is about 7.0 Hz, which is pretty near the Schumann resonance.
The Schumann frequencies shift over time, and go up an down in cycles. Right now, they are higher than ever measured before. They are around 11 Hz for the primary frequency. This is pretty phenomenal, and there's a big argument in the scientific community about what this means for species living on Earth, or about the climate/history of Earth itself. Nobody knows for sure why it's happening or what it will mean to us.
Here's some more interesting articles about the Schumann resonance: