A few years ago I found that many of my friends were looking for help improving their abilities as game masters. Since I'm always on the lookout for tools and methods to improve my abilities, I had lots of resources to recommend. I have compiled them all into a single Google doc.
Take a look! You will find my curated list of map generators, name generators, lore, and anything else you might need to run a tabletop roleplaying game. New DMs will find tons of good stuff here.
D&D Essentials
I periodically update this list. If there's something you think every D&D player should have, or a broken link, please let me know and I'll find a spot for it or fix it up.
At some point I might make one of these for players OSR resources, or perhaps something tailored to setting up content for games in VTTs.