1)   Gear Factory 6
Gear Factory allows you to easily add standard or custom gears to your Drawing. The gear models created are standard AutoCAD solid models that can be added to your assembly drawing as 3D model or 2D entities.
AutoCAD, Shareware, Parts Library, gear, gears, spur, bevel, rack, Autolisp, Freeware,

 2)   AcadCalcStair 02
AcadCalcStair - Stair and Rail Auto drafting program + Calculator for AutoCAD. Main features: STAIRS & RAILS. Parametrical Modeling and Auto Drafting. On the base of parameters the program creates the drawing: Stair Plan and Elevation.
Stair, Rail, Calculator, Slope, Bevel,