Is there a way to offset the default grid? I would like to offset the way the default grid is displayed. 

Currently the thicker grid lines start at 0,0,0 and are spaced 1 blender unit apart.

I am not looking to alter the spacing, I would just like to know if I can change the thicker lines to start at .5 blender units away, either on all axis or just specific ones, say just x &amp; y.

The effect of this assuming the offset is applied to all axis, should be a 1x1x1 thicker grid line cube with 0,0,0 at the center.
N key to open the Properties Display. Change scale to half Blender units. If you want add sub-division of 10 for example for the sub-units. Subdivisions are visible in orthographic mode.