On Linux or UNIX systems, you can install the software as follows :
The package contains the documentation in HTML format. The manual is also available here, and there's a note on Objective-C blocks. The text Objective-C for Unix is also a source of information on the architecture of the compiler.
Instead of compiling those packages yourself, you may want to download RPM packages from Sourcesoft.
More Objective-C packages can be found at Metalab : http://metalab.unc.edu/pub/Linux/devel/lang/objc/.
CheezMUD is not in the /devel/lang/objc directory, but rather in http://metalab.unc.edu/pub/Linux/games/muds/. Another package is SDOC
The Windows version is at Simtel : ftp://ftp.simtel.net/pub/simtelnet/win95/prog/.The latest precompiled package for Sybase/WATCOM is oc319w. zip and the latest precompiled package for Microsoft Visual C++ 6.0 is oc319v.zip. On Windows, you can use this yaccflex.zip port to compile the compiler grammar.
There is also an OS/2 port (for VisualAge) at ftp://ftp.cdrom.com/pub/os2/lang/.
See ftp://sunsite.cnlab-switch.ch/software/platform/macos/src/HTML/MW_C.html or ftp://sunsite.cnlab-switch.ch/software/platform/macos/src/mw_c/ for the Macintosh MPW port.
UTC Bar Chart is a package to generate EPS bar charts with on the horizontal axis time expressed in seconds (UTC, i.e. time expressed in seconds since the Epoch January 1,1970).
Richtext is an X11 / Motif / Lesstif text editor (and RTF file previewer) written in Objective-C and available at http://metalab.unc.edu/pub/Linux/apps/editors/X/.
Here's a screenshot of the Richtext previewer/editor
SortingInAction is an X11 app available at http://metalab.unc.edu/pub/Linux/X11/demos/.
See http://www.rat.se/homepages/ronny/POC.html for a Sybase/Powersoft WATCOM port (for Windows).
It's possible to configure the WATCOM IDE to compile .m files with the POC. Here are some WATCOM IDE config files to do that.