Flat Frog is a templating system created by Paul Lockaby <paul @ paullockaby.com>. The package is actually maintained by Serge Gilette.
It can be found on SourceForge on its project page
Flat Frog commenced life as Smarty-Lite, as it relies on plugins to add in various support whilst the core remains smaller than Smarty.
This WikiBook will provide a series of examples and practical case on the use of Flat Frog
testing