There's http://html5test.com/ (which is only so-so as a test, since last I checked it only tests whether a feature is feature-detectable, not whether it actually _works_ or anything, for the most part; see the "input element types" section in Safari 5, say).
Once IE is passing Acid3 or close to it, Hixie was going to consider working on Acid4, maybe.
Note, by the way, that most of the point of the Acid2/3 tests is not to push new functionality as much as to push correct implementation of _old_ functionality: stuff that's been specced for a while but is buggily implemented. This was less true of Acid3 than Acid2; last I heard the plan was for Acid4 to be more like Acid2 in this regard.
So are you really looking for new stuff, or correctly implemented stuff? ;)
There's http://html5test.com/ (which is only so-so as a test, since last I checked it only tests whether a feature is feature-detectable, not whether it actually _works_ or anything, for the most part; see the "input element types" section in Safari 5, say).
Once IE is passing Acid3 or close to it, Hixie was going to consider working on Acid4, maybe.
Note, by the way, that most of the point of the Acid2/3 tests is not to push new functionality as much as to push correct implementation of _old_ functionality: stuff that's been specced for a while but is buggily implemented. This was less true of Acid3 than Acid2; last I heard the plan was for Acid4 to be more like Acid2 in this regard.
So are you really looking for new stuff, or correctly implemented stuff? ;)