It seems flash carts really started to show up around the time of GBA & NGPC and now the market is littered with DS ones but now you can own one for your NES! It may be a little late for such a cart especially with it's $135 price tag but never the less It's an awsome piece to own in any NES collection.

The cart Takes CF cards, though outdated very cheap and easily obtained on the internet. The case itself as well is cool looking with superb design. RetroZone are the ones responsible and have an awsome catolouge of NES Hacking tools, custom games, blank donor boards and of course 4 awsome empty colored carts to replace the ones you already own.

Check them out @ http://www.retrousb.com/