http://www.ocztechnology.com/products/flash_drives/ocz_throttle_esata_flash_drive
Here's an older 32g that has both. Granted they've opted for a female usb connector for reasons only known to themselves. But the point being, they can lift the lid off this 32g drive's plastic casing, AND fit inside it the 256m.
Bit of black-tape to bring the bulges together, and viola, esata and usb.
The single reason u don't get 256 esata drives is cos of their competition with SSD.
On the Data Traveller, the spacing for the in/out usb port slider would be big enough for a esata controller.