Some more CSS: http://haughey.com/csshorrors/
The w3c CSS test suite: http://www.w3.org/Style/CSS/Test/
Some CSS2 tests: http://www.editions-eyrolles.com/livres/glazman/Tests/index.asp?ID=217554
DOM test suite: http://www.people.fas.harvard.edu/~dbaron/dom/test/