CompactFlash II (CFII)
CFII cards are identical to CFI with some minor differences. For one, CF II Cards are 1.7mm thicker than its counterpart and, secondly, those devices that contain CFII slots are backwards compatible with CFI Cards (doesn't work vice-versa). As with above, these cards are sold in capacity of up to 1GB (2GB and above only work with devices that utilize the FAT-32 file system)
Smart Media (SM)
This memory only card (no controller onboard but required on the device to be used) is used with digital devices pre-2001 and max out at 128MB. Not being so convenient to the advancement of technology, these cards are still available but taking a back seat to all the others out there, especially the xD-Picture cards (see below).
XD-Picture Card (xD)
The "new kid on the block" was developed jointly by Olympus and Fuji to replace the close to extinct SM Cards (previously favored by both companies). About the size of a postage stamp, this tiny giant can hold upto 8GB of data, knocking the wimpy 128MB max SM card out of the ballpark. As this card is fairly new, adapters are available to assist in using with your device/computer.
Memory Stick (MS)
Sony developed the Memory Stick in 1999 to create brand loyalty for their digital cameras and camcorders. Sometimes they are included with the camera or device in question. Most Sony notebooks do include a Memory Stick reader so users can remain within the spectrum of the brand and know their products will work with each other without fail.
Memory Stick PRO (MS PRO)
The PRO card was developed to provide even more capacity than MS (upto 4GB in comparison to the 128MB MS) and greater transfer speed. Most devices pre-2003 will not be compatible as will be certain card readers, with no adapter in sight.
Memory Stick DUO (MS DUO)
The DUO is exactly the same as the MS only half the size. Sony developed some products to utilize the compact card but an adapter is required for media readers to access the data.
Memory Stick PRO DUO (MS PRO DUO)
The PRO DUO is essentially the combination of the above four cards, being a perfect combination of compact size, high speed transfer rates and great capacity.
The exceptionally small size of TransFlash cards (11mm x 15mm x1mm) allows mobile phone manufacturers to incorporate significant amounts of removable storage capacity into their smaller handsets without changing the physical size of the phone. TransFlash is designed to store personal content such as digital images, MP3 music files, video games and other applications, phone settings and personal data.