Yesterday a co-worker showed me how you can, don't know a better word for it, "nest" datums.
Like if you needed and axis from point to point, you can click axis, leave that window open, click points, create your points, close the points window and those are auto-selected for the axis and it places the points in the axis feature. I know it's kind of basic but I thought that was pretty neat.
Then I figured out how you can make an offset plane through a referenced point then right click and select change to offset and it will remove the referenced point and keep the offset distance.
I was wondering if anyone had some other "not so obvious" techniques dealing with datums they'd like to share.