The ability to more-easily (and precisely) locate vertices of pipes. Some ideas:

1) While "Pipe Draw Tool" is selected, ability to use keyboard arrows to adjust a selected vertex (and adjoining lines/vertices) by 1 pixel in any direction.

2) While "Pipe Move Tool" is selected, ability to use keyboard arrows to shift entire selected pipe assembly by 1 pixel in any direction.

3) Add grid (of configurable size & snap settings) with snap-to-grid.