The email to Kindle feature is one of the best features that I've discovered about my e-Reader.
Each Kindle device apparently has its own designated email address, and you can send yourself PDF documents that you don't want to attempt to read on a laptop/phone to be perused at leisure (here meaning, during movements when the trumpets are marked "tacet") with your kindle on your stand.
I've downloaded a few reference books, I downloaded all of the Ian Fleming Bond novels (they aren't very good) a few years ago, and am currently working my way through a biological study of Irondequoit Bay (which is immensely practical) and an old guide to triangulating your position at sea. (Which will hopefully never be practical.)
But the big read right now is the 2025 Mandate for Leadership document, commonly called Project 2025. It is horrifying. It is an astounding exercise in thinking in an alternative reality. It is consistent, organized, and would be incalculably damaging to the country I hope my boys will inherit.
If there is one small silver lining about this incoming President, it is that he appears to be utterly ignoring the recommendations in this document and appointing his friends, cronies, and flatterers instead of the very sincere and capable politicians who would actually be capable of making the Project 2025 agenda happen.