Rizzo is a static site generator, written in Groovy. It is currently usable, but seeking contributors.
If you clone or otherwise download this project, you can run
groovy rizzo.groovy -s . -d published
from the command line (in the project directory), and Rizzo will generate the example site in a subdir called published. (In case you perchance seek a live site as an example: My own site, (incoherencies), is built by Rizzo.)
There is further explanation to be had on the wiki.