International Standards Organisation. Site includes links to many other standards bodies. Ketiv Technologies Product called ReLayerIt that will rename layers in multiple drawings. Los Angeles AutoCAD User Group Phil Kreiker's site. ManuSoft US AutoCAD third party developer of QuikPik and SuperPurge shareware.
Site includes freebies and describes undocumented AutoCAD commands and variables.
Wide variety of CAD and mechanical solutions. MBG Solutions AutoCAD utilities. Group of South Australia. On-line book store. Professional AutoCAD Users Group.