You can use Fink or DarwinPorts to install many X11-based applications, such as the GNU Image Manipulation Program (GIMP), xfig/transfig, ImageMagick , nedit , and many others. Since Fink understands dependencies, installing some of these applications will cause Fink to first install several other packages. For example, since the text editor nedit depends on Motif libraries, Fink will first install lesstif. (This also gives you the Motif window manager, mwm.) Similarly, when you install the GIMP via Fink, you will also install the packages for GNOME, GTK+, and glib since Fink handles any package dependencies you might encounter. DarwinPorts can be used in a similar manner.
You can also use Fink or DarwinPorts to install libraries directly. For example, the following command can be used to install the X11-based Qt libraries with Fink:
sudo fink install qt
There is an Aqua version of Qt for Mac OS X (available from Trolltech, http://www.trolltech.com); however, Qt applications won't automatically use the library. Instead, you'll need to recompile and link the application against the Aqua version of Qt, which may not always be a trivial task. If you want the Aqua version of qt, you can alternatively use DarwinPorts to install it with the following command:
sudo port install qt3-mac
Another interesting development is the port of KDE to Mac OS X. As of this writing, Konqueror had been ported and a port of Koffice was underway. To keep abreast of developments ...