AutoCAD Developers Group Europe - A non-profit association of software developers who are working on applications around AutoCAD. AutoCAD Exposed - Information about undocumented features of AutoCAD, such as commands, system variables, and functions of the ADS, ARX, and AutoLISP programming interfaces. Py_acad - A free software module that makes it possible to extend AutoCAD with the Python programming language, in a similar way as with AutoLISP. Open Design Alliance - An association of CAD customers and vendors committed to promoting Autodesk's AutoCAD DWG drawing file format as an open, industry-standard format for the exchange of CAD drawings. Through the Interface - Site made by Autodesk member that contain information to ObjectARX API development and code samples. ObjectARX & Dummies - Talk about programming using .NET framework and ObjectARX Autodesk API. CADing && Coding - A learning resource for AutoCAD Programming and Customization. AutoCAD.Net programming with C#, VBA Programming, DIESEL Macros and AutoCAD Tips and Tricks.