html5test.com is a site by Niels Leenheer that runs a series of (currently) 160 tests on your browser. The tests are grouped into:
- Doctype
- Canvas
- Video
- Audio
- Geolocation
- Storage
- Offline Web Applications
- Workers
- Section elements
- Grouping content elements
- Text-level semantic elements
- Forms
- User interaction
This is a good start, but help him out with new areas to test! Having a simple "count" did wonders for Acid in many ways, but suffers from the flaw that every test isn't equal. Missing a couple of obscure tests isn't worst than missing a large piece of functionality that is only accounted for in one test for example.