Let me preface this by saying that this site is amazing, and I feel a little spoiled asking for anything else. But, since you're reading this, apparently I am a little spoiled.
I would like to suggest keyboard shortcuts for moving the currently selected brick along any axis. this could work with a combination of the command, option, and arrow keys. for example, if I just placed a brick, I still have it selected, and I want to move it a couple steps to the side, I would hold down the option/alt key and press the right arrow key a couple times and the piece would move to the right. If I moved it a little to far, I would hold down the command key, and press the right arrow key again.
the set up would be:

right arrow = X axis
up arrow = Y axis
down arrow = Z axis

command + (axis key) = move towards axis origin
option/alt + (axis key) = move away from axis origin

the movement would be determined buy the grid setting that determines regular movement.

Like I said, this is a pretty spoiled thing to ask, But it would greatly improve workflow.
Thanks,
SPCOMMANDO.