By Rob Mayoff.
This is a MacOS X screen saver. It should work on MacOS X 10.4 (Tiger) and later.
Download the screen saver disk image. Find the file shown at right in your download list or download folder. Double-click it.
If you're using Firefox, you have to mount the disk image yourself. Safari will automatically unpack it. If you have trouble finding the file, check your browser's download list (Window > Downloads from Safari's menu bar; Tools > Downloads from Firefox's).
Once System Preferences has installed the screen saver, you can move the copy in your downloads folder to the Trash.
The source code. I have donated it to the public domain.
The screen saver runs at six times normal speed in the preview window. When running full screen, it displays your local time.
The idea was inspired by a Mathematica toy. You can read more about the toy here.
My algorithm is a little different than Theodore Gray's. Aside from the obvious difference that I move the locators automatically, I also allow the locators to be at any angle relative to the "trunk" of the tree (which is the hour hand in the screen saver). In Theodore's version, the locators cannot go below the top of the trunk. This change makes many more interesting patterns possible.
The screen saver automatically adjusts its level of detail based on the speed and screen size of your Macintosh. Faster Macs and bigger screens will produce more detail.
Hosannas and brickbats to email@example.com.
This work is hereby released into the Public Domain. To view a copy of the public domain dedication, visit http://creativecommons.org/licenses/publicdomain/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.