Check the article link below for more details and a video
Now, two companies are coming out with small, portable, companion hard disks that massively increase the storage capacity of tablets. And because most tablets lack USB connectors, these external hard disks stream their content to the tablets over a special, local Wi-Fi network they create. No Internet access is required. The content remains on the external device, though you can download files to the tablet’s own memory for permanent storage there.
I’ve been testing the first of these gadgets to emerge. It’s from Seagate Technology, the big hard-disk company, and is called the GoFlex Satellite. It costs $200, and holds 500 gigabytes of data, far more than the 64 gigabytes that is the maximum on typical current tablets.