Features

STDLIB Extensions

In development are several extensions of the standard library.

Either as extension or included in the STDLIB with external libraries are:

STDLIB-ADS Stdlib Adsrx Extensions
Includes some external modules in one ads/rx file.
BINIO- Binary File IO
Included into the STDLIB: BINIO.FAS or stdlib<xx>.arx
ENTMAKE- Entmake templates
Included into the STDLIB: ENTMAKE.LSP
INIFILE- INI File Set and Get
Included into the STDLIB: INIFILE.LSP or INIFILE.FAS
REGISTRY- Windows Registry Access
Included into the STDLIB: REGISTRY.LSP with stdlib<xx>.arx or REGISTRY.FAS (alone)

Discussed at various places and provided by others are other modules as well.

The favorites are:

DICT by David Kozina,

COMBINATIONS by Reini Urban, Michael Puckett, David Kozina and Serge Pashkov

GETFILEM and HTREE by Reini Urban

A lot of noise is also about DCL, GEOMETRY, VECTOR, MATRIX and similar functionality. Vector algebra is important and useful. Same with DCL. Matrix algebra is useful but better not to be implemented in AutoLISP because of numeric instabilities. If one doesn't care about that he might implement it by himself or use some contributed functions. I'm still sceptic. Overall, it would be better to provide wrappers to ObjectARX library functions. Geometry is better supported by external ADS libraries which involve stricter licensing issues, but some interesting and advanced geometric libraries are already available.

You might have a look into http://xarch.tu-graz.ac.at/autocad/stdlib/contrib

or
http://xarch.tu-graz.ac.at/autocad/adsrx/