Canoo WebTest is a free open source tool for automated testing of web applications.
It calls web pages and verifies results, giving comprehensive reports on success and failure. The White Paper provides an overview of the features and the design rationale. Detailed information is provided in the Manual Overview as well as the Install and Troubleshooting guides.
For those of you who've got into it you'll know that test driven development is great. It gives you the confidence to change code safe in the knowledge that if something breaks you'll know about it. Except for those bits you don't know how to test. Until now XML has been one of them. Oh sure you can use "<stuff></stuff>".equals("<stuff></stuff>"); but is that really gonna work when some joker decides to output a <stuff/>? -- damned right it's not ;-)