I just noticed – and perhaps I’m behind the times – that Amazon has supplemented its SIPs (statistically improbable phrases) with CAPs (capitalized phrases). For example, look at the “Inside This Book” subsection about halfway down this page. Amazon explains them this way:

Capitalized Phrases, or “CAPs”, are people, places, events, or important topics mentioned frequently in a book.

As with SIPs, if you click on one, you see all other works that also contain those capitalized phrases. Another cool idea from Amazon. (Wonder how it works in German, though.)