Thank you

... to all the people behind WALS

That is: all the people listed at the WALS credits, the authors of the book and probably many more.

... to the adders of features:

1-29
kaleissin
30-140, 142
Arthaey Angosii
141
This will be added once WALS' own feature 141 is complete, it currently lacks maps

... for the ideas to new website features:

... submitters of useful bugreports