OK, here is my new attempt to memorize one suit out of a deck of cards.
I looked up the method used by the people who do this for a living, like those Grand Masters of Memory, and it's surprisingly simple. It will take some practice, but holy crap, I've already seen some good improvement!
So in about a day, I've gone from remembering two cards out of a suit, to remembering the whole suit. This is totally not because my brain has gone into hyperdrive, but because the method is so effective.
Still, I won't be terribly impressed until I can throw in another suit or two...