Cache Memory 

Removable Memory
DVD Burners
Hard Drives
Zip Drives 
Flash Drives 
External Hard Drives
USB Flash Drives

RAM
DDR and DDR2 
EDO 
SDRAM 

Flash Memory Card Readers and Writers
SD/MMC Cards 
Compact Flash 
Memory Sticks 

Network Storage 
Magneto-Optical Disk Drives 
Servers