@SteveDL It doesn't seem like it would be too hart to build. You'd basically just have a MxM matrix where M = number of keys you want to consider, and then you measure the values and input them. A bit tedious, but it's not hard work per se.
alternatively, you could look at some of the JS based typing speed sites, and see what they use.
@SteveDL it also depends on which keyboard. My physical keyboard is quite different to most, and my mode switches are completely remapped on both my normal keyboard and my notebook keyboard.
So someone typing on a US-English keyboard, will have different results than someone using an International-English keyboard. Still you can probably capture the use case for the majority of lemmings who stick with silly defaults :)