Martin Brown from Grognard Games produced a great short video introduction to Appendix N, the influence the works therein in had on D&D — from thieves and paladins to plane-hopping and alignment — and the inspiration those works can provide today.
It’s a bit surreal for me, though: He’s called Martin as well, and is also English, and I recognize an awful lot of the books on his shelves, but he’s handsomer than me and introduces Appendix N much better than I could. I’m also officially jealous of his bookshelves.
All that aside, you should watch this. It’s quite good.
(Thanks to Erik Tenkar of Tenkar’s Tavern for the link.)