I took over as GM for the Shadowrun Rat's Nest group for a while. The group stole a ton of chocolate at a run in Seattle and now they're trying to sell it to the Irish mob in Boston. I planned to give the characters a day in Boston to get their bearings (and to give the mb time to examine the chocolate...wich is fake and not made form cocoa, a fact the players would rather keep secret).
So they do a bit of sightseeing and I mention the Boston Aquarium. They go there and since one sourcebooks says that there are merepeople there, I mention that as well. Merrows, but I couldn't remember and went with Selkies. They are sentinent beings, but their former home, the Boston harbour, has been polluted and they have been spending the last twenty years in that aquarium.
You probably see where this is going. The characters are already planning a run on the aquarium to free the Selkies and, here come the part I really love, want to take them to Seattle to set them free there. Through several airport security checks - at least they do have their own plane - and with hundreds of miles of perfectly good coastline just outside Boston. But I'm not going to spoil the fun and say anything.