Passmarked is THE tool I've been looking for to check the quality of websites (mine & clients'). The open source list of tests makes it incredibly useful and flexible for integrating into the development workflow. It's only just been launched but there's already a tremendous amount of coverage that will only get better as more people contribute.
The fact that everything is in one place and that some of it is community driven has been amazing for actually learning beyond quick fixes.
Pros:1 month in and this is the best website optimization tool I have ever used
Cons:None when compared to any other tool in the category.
PH should pay Passmarked for all the new aquisitions.
Pros:Great overall product
Cons:Needs further community participation, but great start.
The tool I wish I'd built!
Pros:Not upselling me a "quick fix" (like most "grade my site" tools)
open source = transparency
community driven weighting & docs
free
Cons:Not found any so far (only a day in!) :-)