Theme engines
Haml (Theme engine)
Haml theme engine for Drupal.
Requires you to download phpHaml, extract to the themes/haml folder and presto. Don't forget to use *.haml on your template filenames.
ETS - Easy Template System
ETS, or Easy Template System, is a very clean template system that enables you to transform a set of data to any type of document.
Sample Themes
Awesomengine
Awesomengine is the most awesome engine. It allows for embedding of PHP code, not only in html templates, but in css files, allowing for dynamically set CSS. Otherwise, it is nearly entirely identical to the phptemplate theme engine.
Zengine
The Zengine theme engine is a CSS-oriented theme engine based entirely on PHPTemplate.
It is the continuation of the Zen theme project. Zen was designed to be a great starting theme, but this presented a problem because users who have already created their themes were unable to benefit from further development of the underlying Zen framework. Zengine attempts to solve the same issues as Zen in a more robust way which allows improvements to the underlying framework even for those who have already created their themes.
XTemplate
The XTemplate theme system uses templates to layout and style Web pages. It separates logic (PHP), structure (XHTML/HTML), and style (CSS), making it easy for designers to create or modify templates by working on XHTML/HTML and CSS without having to worry about any PHP coding.
This engine is compatible with both PHP 4 and 5 and is designed to be used with Drupal 4.7. I have no plans to update this module for 5.0. If someone would like to contribute a patch I'll be happy to review and commit it.
wgSmarty theme engine
This theme engine is no longer supported
Since Drupal 5, and even more so in Drupal 6 and beyond, the 'other' smarty theme engine (http://drupal.org/project/smarty) works much better. So there is no longer a need for wgSmarty, which is a good thing as it did confuse people anyway.
wgSmarty is an implementation of the Smarty template engine as a theme engine.
Advantages
- Template files are easier to create and maintain then with PHPtemplate
- Templates are compiled into PHP to avoid speed and memory issues with search-and-replace template engines like XTemplate
- wgSmarty is much more closely integrated with Drupal than the existing smarty theme engine
Disadvantages
- wgSmarty is currently experimental and is only available in CVS
- There is very little support for wgSmarty: even when it is released, it will still be poorly supported in comparison with PHPTemplate

