That's a pretty wide-open question.  Certain things can be generated in varying degrees of automation.  For one example, try STAIRS.lsp, available >here<.  [It also contains a command for a section as well as the plan view of the topic heading.]  It takes user inputs and starting points and generates elements from there.  If you have a specific kind of thing you want to draw in an automated way, Search around that Cadalyst CAD Tips site, and in places like the AutoCAD Customization Forum and other sites (look for The Swamp, CadTutor, AUGI, and there are others you'll find links to in ACAD Customization threads).