Hm...alright, here's a good one I thought up.
The Earth produces gravity. Above the Earth there is field of matter which produces the same gravity as the Earth. This nullifies the Earth's gravity and explains why gravity is weaker further away from the Earth.
Both the field and the Earth are travelling upwards at 1G (being pushed by dark energy, of course) which explains why you appear to be pulled down towards the Earth.
The only problem is that the field needs the same mass as the Earth, so it's either the same density and area as the Earth, in which case it must be invisible, or it's extremely high density and extrememly low area, eg, a kind of black hole...