Is there a way to print a list of games missing from your collection?

I found the collection export, which is great starting point, but I was hoping there is a missing from collection export. Basically a list of games I need to complete the collection for X platform.

For viewing items you're missing from a specific platform, the closest (and only partially implemented feature) would be under Browse Database -> By Platform where you could filter the list by "items not in collection." Unfortunately, NES is one of several platforms that's not included yet as it is still a WIP. The larger collections take a fair bit of time to add unfortunately and all the curators who contribute to the site have extremely sporadic schedules.

Awesomeness! I will give it a whirl and see what it gives me.
If I keep buying at my current pace, it will take me 4-5 years to complete NES, so this should do me for the time being...

Yep, as @dhobo mentioned, the best place for this would be the Browse Database -> By Platform page. NES is actually something I've been working on, but it's not quite ready yet. Hoping to have a nice bundle of new platforms on the page in the next week or two. The NES won't be one of them, but some are Nintendo platforms

As far as printing out a list goes, it's not ideal, but you could add everything to your wish list and then export it. I'll make a note of maybe adding an export option to the Browse by Platform page.