Reptile Playground is an interactive tool for creating and drawing substitution tilings. Substitution tilings are tilings of the plane which are created by iterating a set of rules, called substitution rules. Below are some screenshots of the program in action.
Reptile Playground was created as a course project, and the documentation is still "in the works". Many of the features, and a description of how to use them, can be found in this report.
Also, several videos demonstrating the features can be found here.
Update: January 3rd, 2012: I have implemented the following new features:
Reptile Playground is written entirely in Java. As such the executable jar files provided here should run on any platform supporting Java 1.5+. It is confirmed that these files work on Windows XP, Vista, Ubuntu, and OSX 10.5+. If it does not appear to be working on your Mac, please ensure that only Java 6 is being used. This can be adjusted in "/Applications/Utilities/Java Preferences".
I would like to thank John Hendry for many suggestions to improve the program, as well as discovering many of the bugs in the initial version.
Please send me an email to suggest features and report bugs. If you have created interesting tilings with this software, please send those too! I am still documenting some of the source code, and my plan is to eventually make it available on request. My email is p3nichol [at] uwaterloo.ca.