I use this USB host cable and it works great. Have tested it with my 750gb Oyen and 320gb WD Passport external HDD's, several usb flash drives (8-16gb), San disk USB memory card reader, and a USB keyboard.
For those having issues getting their Xoom to recognize USB storage devices here's what I've got and did to get it to work: I flashed my XOOM (3.1) to the 2.6.36.4 Tiamat_Xoom-v1.4.4-Full_Throttle Kernel and was unable to get the USBMount to recognize drives or storage at first. I installed USB Mass Storage Watcher from the market (it's free) and it works awesome! Can mount any storage I want (NTFS, FAT16/32, HFS, HFS+, EXT2, ETX3, EXT4) with any capacity. I think this app will work with any rooted Xoom (or other devices). Under my Kernel my USB host is located under/usbOTG.
Hope this helps.
For those having issues getting their Xoom to recognize USB storage devices here's what I've got and did to get it to work: I flashed my XOOM (3.1) to the 2.6.36.4 Tiamat_Xoom-v1.4.4-Full_Throttle Kernel and was unable to get the USBMount to recognize drives or storage at first. I installed USB Mass Storage Watcher from the market (it's free) and it works awesome! Can mount any storage I want (NTFS, FAT16/32, HFS, HFS+, EXT2, ETX3, EXT4) with any capacity. I think this app will work with any rooted Xoom (or other devices). Under my Kernel my USB host is located under/usbOTG.
Hope this helps.