I have, as one might expect, a considerable number of bookmarked pages. Here are some of the most useful / interesting / novel / enjoyable of those.
Artvee - High quality, easily-searchable public domain art.
2D Star Map - I like the one above better, but this one has hexes!
Azgaar's Fantasy Map Generator - A gift that keeps on giving.
generated.photos - Algorithm-generated human mugshots.
500 Fantasy Character Portrait Icons - All made using Artbreeder, and thus free to use.
300 OSR-ified Pathfinder monsters - Just so.
500 level-less spells - via Ten Foot Polemic
Old Book Illustrations - Public domain.
Jalopy Design: Making a Zine - David Schirduan swoops in with helpful advice for beginners.
The Phrontistery Dictionary of Unusual Words - For when you want to sound like Gene Wolfe.
Map to Globe - Takes a map, puts it on a globe
Lady of Hats' fantasy art - Public domain!
Hex-a-Day - Three huge hexmaps
Manyfold Theory of RPGs - via Levi Kornelson
Mothership Character Generator - via Tarsos' Theorem
Draw all roads in a city at once - If you are running EE, you need this.
Diagrams.net / draw.io - the most useful thing on this list, bar none.
Town and Settlement Rules - via Pilgrim's Temple
THE GENETIC TAROT - Chargen?
Reverse Dictionary - Search for words by their definitions.
Bayeux Tapestry Generator - What it says on the tin.
Forgotten Female Fantasy - As the tagline on the site says "reviewing vintage woman-authored SFF". it's great stuff - hidden gems and horrible pitfalls alike.
Standard Ebooks - Public domain ebooks
Inexorable (Taylor Leong) - A short comic about Narnia, and the god named Tash.
Thirty Years (Taylor Leong)