You will need a Shielded eSATA to SATA cable. Buy one here.
Personally Tested USB Devices
(+) = working, (-) = not working, (*) = not tested
XMB Linux
SmartDisk USB 3.5" floppy - +
Atech Flash PRO-9 USB 2.0 MultiCard Reader + +
Logitech Wingman Rumblepad + +
USB Mass Storage** + +
Logitech Quickcam Pro4000 - *
Sony PS2 IR remote via RadioShack USB + *
SonY PS2 Dual Shock controller + *
USB Keyboard and Mice*** + +
**Multiple branded USB flash drives, 2.5" HDDs, 3.5" HDDs
***Dynex USB Keyboard and Mouse Combo, Logitech Cordless Duo MX, others.