LCX for Mac OS X
If you are looking for a Mac LDraw editor, check out Bricksmith.
LCX is written by Kenneth Dyke and hasn't been modified since 2002. LCX is an unsupported Cocoa application that was created for a Quartz Extreme demo at the 2002 WWDC. Ken got too busy to finish it, and he let me (James Reynolds) update and distribute it.
System requirements: The oldest OS/hardware this was tested on and worked with was Mac OS X 10.1.5 using an iBook G3 466. So anything newer than that shouldn't have a problem at all.
This isn't a final release by any means. But I really wanted to get this out because it has some cool features.
Instructions
Before using LCX or any LDraw system tool, you need to download an ldraw folder first. If you don't already have one, you can do this by visiting the LDraw.org Macintosh getting started page.
Then open LCX. Set your ldraw folder by opening the preferences.
LCX does not open a document when first launched. You must select "File" -> "Open" first.
LCX lets you open sub models and parts. This is an interesting feature that most other ldraw system tools don't have. It might be useful in creating parts.
It also has an option to show BFC (back face culling) compliance.