Catenary program makes it easy to create or draw a catenary curve as a polyline by specifying the start and end point and the length or sag and optionally a diameter.
FixRefs - powerful AutoCAD reference manager app gives you a lot of options to make changes on external references on multiple drawings.
Layer Palette allows manage layers in BricsCAD without leaving drawing screen. Customizable view, multiple layers tasking, this will make managing layers much more easier.
Rebar - is a BIM-like Rebar Callout - Automatic Rebar Table - Dynamic Beam Detailing app for AutoCAD.