My most recent example occurred with the purchase of my new camera. Rather than taking fairly standard camera memory, it uses xD cards. They are ultra small and cute but my laptop doesn't accept them. I hate the lengthy cord that came with my Olympus SP-350, so I went in search of, yet another, adapter.
I ended up buying a little, key chain USB device. It's not quite as easy as a slide-in adapter, but I could use the device to carry around a half-gig of work files. All computers seem to have a spare USB port; unfortunately, not all sport easy access from the front panel. So, I did manage to shift all my USB devices and ended up with a spare 4-port USB connector that will go directly into my box ...