Don’t know if this is already on the list…
When placing a radius or diameter dimension object, if I have for example Ortho active and set to 45°, that I can pull out the first leader line and it will be constrained to the nearest set ortho angle.
Or, that I can click somewhere on the arc/circle to be dimensioned, find a snap point somewhere, but instead of snapping there, I hit tab to freeze the angle - then the command allows me to pull the line out further along the same line or shorten it before placing the point.