To put them up on a wall, Ikea sells some good shelving that many other users here have exhibited in their collection photos.
If you want to show them labels-out (which I don't recommend because they will fade over time) you can nail your own strips of wood into the wall. I'd hit Home Despot and get some simple square wall moulding and cut it to length of your wall. When you get it home, mark your measurements so that they're exactly the height of a NES cart. It's important to get the tolerance to almost zero, less than 1/16th of an inch, otherwise the game will just fall out and onto the floor
This is good to a "runner" or border along the top of shelving, but I'd be hesitant to do a whole wall like this, it takes really stupid exact measurements. But it's easy to swap out games when you get something better you want to see!
