For those who want to experience the fun of downloadable content but refuse to play on any system but their vintage NES, the impossible has happened. RetroZone has released the game Glider for the NES. For $US 42, you get a quirky flying game (in which you navigate a miniature glider through a house) complete with additional downloadable levels that can be added by flashing the cartridge's built-in memory. And the DLC updates are actually free.
The only catch is that to download new content, it appears you need to first mod your NES with RetroZone's $US 70 USB CopyNES. So what could have been a fun afternoon quickly escalates to a part-time hobby investment.
Glider [RetroZone via Joystiq]