I use the case logic small external hd case found at CompUSA. The 770 fits perfectly under the strap and the other half has a storage area that is plenty large enough for me to store the cable, 3 memory cards w/ extender, a card reader and the nokia bag that came with the unit. The case is reinforced, so it offers a bit more protection.

I was considering the aluminum case, but wanted the ability to store extra goodies. The case logic is as wide as the 770 and about 2 1/2 to 3 times as thick as the unit. It was well worth my money to have everything I needed in one case with a small form factor.

Check out the link below:
Case Logic Portable HD Case