Epic Slant Press has an article on the lessons they learned from their Kickstarter game. I found it to be interesting for the insight into the game industry.
Rules Design
Mutant Future RPG
Mutant Future is a retro-clone of the old TSR Gamma World Game. There’s a commercially available printed version, but you can also download an artless version if you just want the rules.
Templates For Playing Cards
If you’re designing your own games, here’s a page with some pdf, ai and psd templates for playing cards of various sizes. I’ve taken to making unit cards rather than roster sheets for players to keep track of information in my games.
Creating Data Driven Graphics In Photoshop
This tutorial would be useful for generating large sets of gaming cards.
Dice Probability Calculator
Anydice is an online probability calculator. Useful for game and rules designers.