htmlfixture
HtmlFixture is a Java FitNesse fixture used to exercise and test web pages. It acts as an adapter between FitNesse and HtmlUnit. It permits you to make assertions in a FitNesse page about the structure of a page and to navigate between pages. You can also fire java script, submit forms, "click" links, etc.
To get the source, you must use Subversion. The repository is here. To get the latest, bleeding-edge revision get trunk. Previous releases are available under tags.
Note that htmlfixture uses Maven to build, and it uses a customized HtmlUnit library whose compiled jar is also available in the repo, alongside htmlfixture.
Compiled jars of htmlfixture will usually be available in the jars directory.
There's also a web-browser interface to the repository.