I have learned literally countless things from proofreading. (I say "countless" and "literally" because in my tipsiness, I tried to count them, and I was incapable. Could be the wine, or could be the sheer number of things I have discovered by proofreading various Slavic dissertations and sci-fi wonders). Here is my fun fact of the day, which perhaps you were unaware of:
There is indeed a kind of coffee called "long black." This is not a typo for "tall black coffee" as a certain proofreader may have imagined. A long black is much like an americano; it's a couple of shots of espresso poured over hot water.