EditorialGuy - 6:23 pm on Jul 16, 2013 (gmt 0)
Re internal search:
My wife and I have been publishing information sites since 1996, and only a tiny fraction of our readers have ever been willing to use internal search (even when we've had a big search box at the top of every page). I think a lot of people have the idea that you use search to find a site, and once you're on the site, you use navigation links.
Ditto for social buttons. We used to have Facebook "Like" and Google+ "+1" buttons, but very few readers used them. Our readers preferred to send us (and continue to send us) "thank you" e-mails.
The moral here (IMHO) is that the techniques for being "useful to users" vary not only with the type of site (e.g., e-commerce or information), but also with the audience.