3 links
Autocad 3D Utilities
schorsch.com
A collection of free utilities in Autolisp, ADS and ARX for 3D modelling and exporting to visualization systems.
AutoJournal
autojournal.net
Links AutoCAD with the journal function in Microsoft Outlook for time and billing.
CADDee.com
caddee.com
A few free AutoCAD utilities for download, with instructions and a support forum.