Bank on this:
I rather thought those little

thingies looked like gold, found a building that gave +50%

(a whole stack of em!), and beelined Banking. Needless to say, I was rather disappointed when my research rate (with the slider at ~80%) didn't improve after building Banks.
They're all out to get me!:
In my first game, the AI settled a spot which I was eyeing for my 5th or 6th city. Interpreting this as an act of aggression, for my second game I attacked any and all rival scouts who were in "my" territory planning to settle "my" land, declaring war as early as the third game turn.
Then again, maybe that wasn't such a bad idea.
Corporations = GPS?:
I had a non-coastal city with coastal tiles in its BFC. Tried to build a lighthouse. Where's the option? What's going on? I checked the Civopedia and saw that some kind of Lighthouse went obsolete with Corporation. Ah! That's it! But the existing Lighthouses still worked, so "obsolete" just means you can't build any new ones.
So for the next 2 or 3 games, I made a point of rushing to settle new cities and build lighthouses everywhere just before researching Corporation.
Tally me Bananas:
After researching Calendar, I built a banana plantation three tiles away from my capital (well within cultural borders). I went into the city screen and realized I couldn't
work that tile.
Well... it stands to reason that if no one is working the bananas, then there are no bananas being harvested and thus no health benefit. So I built another city in a lousy spot nearby.
Along that same line of thought, I razed an AI city because it was right on top of an ivory tile and then built a new city right next to it. 'Cause I needed the ivory. No camp, no elephants, right?
Vassals, come forth!:
I was right excited the first time I switched to Vassalage. After the anarchy ended, I sat back and waited for a special screen to pop up where I would pick out my "+12 free units" and (presumably) place them in my various cities as desired.
Cheers.