This isn't so much for anyone else's sake as for me to chronicle it while I remember it, but I was playing a game of
SettlersXplorers over on AsoBrain Games, and was up 13-11-12 in a 15-point game. Come my turn, I had six wood, two brick, two cloth, and five paper (I already had the paper metropolis). I had the brick port, and level one coin and cloth. I could have just stolen the merchant, put it on wood, and built a settlement easily, but I figured out I could do much better...barely. So this is what happened:
Merchant to wood, for 14 points
Traded 6 wood and 2 brick for 4 cloth (6 cloth)
Upgraded from Market to Trading House and Trading House to Merchant Guild with 5 of the 6 cloth I now had. (1 cloth, level 3)
With my new ability to 2-for-1 any commodities, I traded 4 paper for 2 cloth. (3 cloth)
Using my Crane card that I happened to have, upgraded to Bank, grabbing metropolis for two points and finishing 16-11-11, much more dramatically than just building a settlement.