The website says:
The New Age Movement is difficult to define because "there is no hierarchy, dogma, doctrine, collection plate, or membership." It is a collection, an assortment of different theologies with the common threads of toleration and divergence weaving through its tapestry of "universal truth."
The New Age movement has many sub-divisions, but it is generally a collection of Eastern-influenced metaphysical thought systems, a conglomeration of theologies, hopes, and expectations held together with an eclectic teaching of salvation, of "correct thinking," and "correct knowledge." It is a theology of "feel-goodism," "universal tolerance," and "moral relativism."
I think that summarizes it well, although it doesn't really nail down a definition either. I'm going to have to peruse this website more. And I'll try to find some sort of idea of how the New Agers define themselves too.
Right now, I'm leaning towards a definition that includes a "thirst for knowledge of the hidden universe." But it's not based upon scientific principles, like those who study quantum physics or astronomy. It's based upon metaphysics. I'll return here with more later.