Cards | USB Flash drives

Type		Size	Compatibiity
SD	Secure Digital	128MB-4GB	Canon PowerShot, Pentax, Nikon, Palm (newer)
SDHC	SD High Capacity	4-32GB
mini SD	miniSecure Digital	128MB-2GB	Cell Phones
micro SD	microSecure Digital	128MB-2GB	Cell Phones
MMC	Multi Media Card		Canon PowerShot
CF-I	CompactFlash I	128MB-8GB	Canon EOS & Digital Rebel, Olympus, old Nikon, old Palm and Pocket PCs
CF-II	CompactFlash II	128MB-8GB	Microdrive, Olympus
xD	xD Picture Card	64M-1GB	Fuji, Olympus
MS	Memory Stick Pro	512MB-4GB	Sony
	Memory Stick Duo Pro	256MB-2GB	Sony
SM	Smart Media	128MB	Fuji, old Olympus

Other types of cards:
SIM - Subscriber Identity Module for mobil phones
Smart card or or integrated circuit card (ICC) (ISO 7810 and 7816 Card Standard)
  Credit Card with imbedded ICC.
PC Card - PCMCIA - 85.6 mm long and 54.0 mm wide

Type	Size	TransferRate	Price
SanDisk Secure Digital
Extreme III	1GB	20MB/sec	$140
Extreme III	12GB	20MB/sec	$780
Extreme III	16GB	20MB/sec	$1050
Ultra II	1GB	10MB/sec	$80
Standard	1GB	2MB/sec	$50
Ultra II	2GB	10MB/sec	$120
Standard	2GB	2MB/sec	$100
Transend Secure Digital
High Speed	4GB	22MB/sec	$220

Note: Above types are SanDisk names; other manufactures use terms like High Speed or Extreme Performance for faster cards.
There is a brand name Ultra who's basic card is a 40X write speed. Price a/o Mar. 2006

Transfer Rate
13X	2MB/sec
60X	9MB/sec
66X	10MB/sec
133X	20MB/sec
150X	22.5MB/sec

These speed notations may not be consistent among manufactures.
Write speeds are slower than read speeds.

Most camera manuals don't tell you what speed of flash card you should buy, usually recommending a type and maybe a manufacturer (who has often paid to be included in their recommended list). If your camera has resolution under five mega pixels, the speed rating of the flash card won't matter much. In fact many cameras will not work well with ultra high speed cards of 133X and 150X speeds because of the special formatting used to achieve these high speeds. The improvement you are likely to see in a higher rated card will be minimal and undetectable.

Professional photographers using professional-grade cameras should use high-speed flash (40X - 150X). If your camera has a pixel rate more than five mega pixels, you will benefit from a flash card with a higher speed rating. If your camera has a resolution less than five mega pixels, simply use cards rated less than 40X, this way you can ensure compatibility and not spend money unnecessarily on higher rated cards.

Secure Digital:
Secure digital cards or SD card for short, is a derivative of the now widely used Multi media (MM) cards. The SD's data transfer rate is up to 10MB/sec, which is four times faster than the MM cards.
The outstanding feature of SD cards is that, it is in compliance with SDMI or Secure Digital Music Initiative. This feature of the card will not allow for example, a copyrighted music to be downloaded from any source. Almost all electronic manufacturers are coming up with products, which support the SD cards hoping this would be the next big thing in memory cards. Products, which support SD cards, are almost backward compatible with MM Cards but not the other way around.

SanDisk Ultra II Plus SD Card can be folded to fit directly in a USB port. 1G = $90

CompactFlash (CF) cards provide complete PCMCIA-ATA functionality and compatibility and can be used in a PCMCIA slot with an adapter.
A Microdrive is a CF Type II card and can go up to 4GB.
CF Type I thickness is 3.3 mm; CF Type II thickness is 5 mm
The CompactFlash card specification version 3.0 supports data rates up to 66MB/sec and capacities up to 137GB.

32GB USB flash memory sticks (thumb drives), now available at $120, are an alternative for backup.
Listed Data Transfer Rate are 19MBps Read 13MBps Write
Actual for a 32GB flash stick are:

	               Sequential Read       Write
32 GB Corsair Flash Voyager 22 MB/sec  10 MB/sec
32 GB OCZ Rally 2           30 MB/sec  22 MB/sec
32 GB Patriot Xporter XT    31 MB/sec  17 MB/sec

USB 2 was reported to be slower on Macs (may be improved in panther OS X 10.3)
See: X-Bit Labs rreview of 32 GB USB flash drives:

See:
Flash USB (thumb) drives
Speed Tests at MobileTechReview.com
TigerDirect.com/
Reviews and FAQ: Memory Cards at MobileTechreview.com
SDcard.org