SmartMedia (aka solid-state floppy-disk card or SSFD) was originally developed by Toshiba.
These cards are very thin and thus are limited in their capacity. I think the biggest on the market at the moment is 128MB. Mostly being phased out from cameras, they were used in some old Fujifilm models.
SmartMedia cards erase, write and read memory in small blocks (256- or 512-byte increments). This approach means that they are capable of fast, reliable performance while allowing you to specify which data you wish to keep. They are small, lightweight and easy to use. They are less rugged than other forms of removable solid-state storage, so you should be very careful when handling and storing them.