This is a list of resources I tend to rely on if I get stuck.
10 Things Every Game Needs – the best breakdown of the essential parts of game design I have come across.
The Art of Game Design: A Book of Lenses – fantastic book on game design. Comprehensive guide to designing great games.
Monkey-X Programming Language – Monkey-X language documentation
Less Milk – another game creation blog with tutorials and examples using the PhaserJS framework
Level UP Rails – some fun and useful exercises for leveling up your rails skills
Sinatra RB – contains documentation and quick start guide for the Sinatra web framework
Make Art for Your Games
Make8BitArt – simple and easy tool for making 8 bit graphics for your game
Stack Overflow – a question and answer site for all things programming related
Clean Code – a great book on writing better code