In my Simpletest Session in Essen , there were a few discussions about Selenium. With Selenium IDE you can click Firefox Tests together. Boombatower have recently created an online module you can use to convert Selenium PHP data to Drupal Simpletest format for export. It isn't stable yet, and is still only for D7, but I think it will interest many, and will certainly make tests a lot easier. Selenium to Simpletest