You really can't say enough about the retro power of old NES cartridges. An entire generation grew up on these things, so any chance we have to use them in our day-to-day lives is greatly appreciated. Which is why these NES cartridge hard drives are so great.
It's pretty simple, really: Etsy sller 8-Bit Memory takes old NES carts, pops a hard drive inside, cuts a small hole in the side for a USB port, and bam, you have an external hard drive. The standard model is $120 for 250GB, but he'll make any size for you and with any game for an extra charge. How awesome is that?