Additional Placements is a Vanilla-lite mod that allows you to place blocks in new orientations.
No new items are added - instead, the placement logic of the original blocks is modified.
Currently supports (includes most mod-added as well):
Slabs - allows vertical placement
Stairs - allows vertical placement, and stairs will connect vertically as well
Carpets - allows placement on walls and ceilings
Pressure Plates - allows placement on walls and ceilings
The "testing spheres". These odd shapes contain all 108 different possible stair block states and all 6 different possible slab block states, for testing purposes.
The placement logic for slabs and stairs.