I posted threads on a few little tools I've developed over the years, but I was reminded by a recent thread that I ought to upload the PDFs for people to play with.
So, we have:
contour_ang for measuring slope angles from
contour spacingunm_grt a grid measuring tool for
Editorial Alpina 1:50k 5km grid mapsmap_grid_publish a
1:25k vernier romerplotter_grids a combined vernier romer/portland plotter
navtool a combined vernier romer/portland plotter/ruler/slope tool
These are all written in PostScript, and designed to be configurable, so if you have any special requirements, they can be met. They generally include multiple copies for efficient use of a transparency, or include multiple different versions to show the sort of options that can be selected.
They're all intended to be printed onto transparency (ideally with a colour laser printer).