While looking for resources for that game or that scenario you come upon the occasional online gem! These are a few that we have found most useful.
Being a Great DM
- Online DM Screen – quick info for the 5e DM
 - World Anvil – worldbuilding tool for Tabletop RPG Storytellers and Authors
 - How to be a great GM – Youtube channel
 
Encounter Building
- Kobold Fight Club Plan, Manage, Run your 5e Encounters
 - Unearthed Arcana – Wizards of the Coast Unearthed Arcana: Encounter Building (PDF)
 - Sky Flourish – Great Article on Building Encounters in Fifth Edition Dungeons & Dragons
 
General Great Stuff
- 5etools – A suite of tools for 5th Edition Dungeons & Dragons players and Dungeon Masters.
 - Open5e – Open5e aims to be the best open-source resource for 5e content.
 - Fitz’s roleplaying stuff – another player who has some great idea
 - https://jsigvard.com/dnd/ – Usefull Lists & Tables
 - Merric’s Musings – Great Reviews and advice
 - Weight Chart for Non-Living Substances
 - Randomise a List – A form to permit you to arrange the items of a list in random order
 
Tools for the Table Top
- Paper Tokens Generator print round or squared creature tokens.
 - Token Stamp – Make a Roll20 Token
 - Printable Heros creates print-ready paper miniatures
 - Paper Mage Paper Miniatures
 - Printable Card and Tent Cards
 - pre-made characters
 
Other
- RPG Table Finder – With over 100s of Tables from around the world, you can find your next role playing group here
 
Generators
- donjon RPG Tools almost everything
 - Random Generators of Things
 - Name Generator
 - Location Generator
 - Random Magical Effects
 - NPC Personalities
 - Fantastic Descriptions
 - Dungeon Master Tools
 Wizardawn - Kasson great content, generators and more
 - Tavern/Menu Random Generator
 - Spell Book Generator
 - NPC Generators
 
Maps
- Planet Map generator
 - Map Building – 
inkarnate  - Map Building – pyromancers
 - Medieval Fantasy City Generator
 - Toy Town – 3d visualizer for Medieval Fantasy City Generator
 - Fantasy-Map-Generator (azgaar)
 - WONDERDRAFT – is an intuitive yet powerful fantasy map creation tool for 64-bit Windows 10, Linux, and MacOSX.
 - DUNGEONFOG – Online map maker & authoring tool for RPG game masters
 
Tools for Digital Table Top
Actions & Combat Cheat Sheets
Note: These references provide the same information, but have different presentations. Pick the one you like best.
- Player’s Actions and Effects QuickRef – Website based
 - Player Reference Sheet – One page, dense and thorough
 - Combat Cheat Sheet (Basic) – One page, simple
 - Combat Cheat Sheet – Rolling initiative, actions, attacks
 - Combat Reference Sheet – 2 pages
 - Player Reference Sheet – 4 pages, detailed
 - Checks and Combat Cheat Sheet