The C64 DTV is a modern (and extremely cheap) clone of the Commodore 64 with a set of built-in games -- and keyboard and disk interfaces. To provide persistent storage and thus make it a useful C64 system, it would be neat to have a flash-based storage device that emulated a 1541 disk drive. Since this would only need a small microcontroller and a flash chip, it could probably be made small enough to fit inside the original DTV case.
Looks like Jim Brain had the same idea: his uIEC is a Compact Flash-based 1541 emulator.