Sometimes thinking up crazy ideas can lead to new and usable products... down the line. Over the past couple of years we've ended up with UberGROMS and FinalGROMS for the cartridge port, TIPI's and other stuff that works with the side port...
... but what about the joystick port & video port?
I'm sure a new plug & play device could be devised that works with them. The joystick port could be the connection point for the new and yet unknown item, while the RF port could be used to steal some power (if necessary).
... but what would this item be?
Activate your imaginations! What do we not yet have? What would be cool to have? Maybe by this time next year we could have the next new thing to play with.