Various freeware LISP tools for AutoCAD:

MAZE.LSP - random maze generator for AutoCAD, converted from CLISP

TotalLayouts.LSP - automatic reactor creating a field variable with the current number of DWG-layouts (autoload this)

COG3D.LSP - display center of gravity point for solids and regions

CenOf.LSP - display XY(Z) or osnap center of selected object(s)

CMDtimer.LSP - reactor-based timing of AutoCAD commands - track execution time of native commands

Txt2Ref.LSP - replaces drawing texts with block references of the same name

mPDFimport.LSP - import multiple pages from a PDF file

SelectSimilar.LSP - extended version of the SelectSimilar command, also for LT and AutoCAD web app

More freeware tools available on https://www.cadforum.cz (and follow ARKANCE CZ / CAD Studio on LinkedIn and on Facebook - @ArkanceCZ)