Nice as it is, unfortunately it will be of little help in normal life.
Typical you'd like to read a specific book and then want to know which store offers it DRM-free (and is also shipping to your country...), not the other way around.

So I am still stuck with my old routine:
Search a couple of the bigger sites that sell ebooks to where I live, check if the desired book's store pages say "DRM-free", or at least some unobtrusive DRM technique like watermark only.

And if it's not available DRM-free anywhere i looked, at least I have done the best I could and feel not guilty about setting sail instead...