I already found a post with this website but honestly don't find it too useful. Why? It just lists and stats all scopes used in default packages without respecting 90% of them don't need to be handled by color schemes.
Without any background info, the overwhelming number of listed scopes would prevent me from even thinking about creating a new color scheme.
It's more important to know which minimal set of scopes need to be addressed to make a color scheme work with all syntaxes.
Much effort has been put into the default syntax packages to ensure they use the same scopes for similar entities in the past few month.
The next step is to ensure all color schemes at least provide a minimal required set of scopes to make them work properly with all default syntaxes. This is what a package like ColorSchemeUnit could/should provide some automatism for.
Today many custom color schemes look good for one or two syntaxes as the author created them for them. In some cases you'll even find certain language references being used directly. This prevents many user from using them as they would need them to look good for other languages, too.
Such issues must be solved somehow.
A package telling which scopes need to be added to a scheme to be accepted in Package Control would help the author much to find their way to follow all the conventions.
PackageDev already helps much with creating syntax files as it provides auto-completion for scopes per convention. Something like that is needed for color schemes, now.