Ha, thanks. I'm glad they were so well-received. I worried whether some might feel it "wasn't self-contained enough", but assuaged that with the fact that we'd previously done 2 topic challenges based off this particular external site, had another one coming up (which is here now, quite by coincidence), and it's very much in the community's sphere of influence given the number of references that get made with links dropped in comments (
e.g.).