I enjoy reading Damion Schubert's MMO-focused blog Zen of Design.

• The Zen Lexicon is especially recommended.

Peter Molyneux is one of the most ambitious & imaginative designers.

• ...although his games famously often fall short of expectations.
• I share his belief that emergent behavior through Simulation and AI is probably the most interesting area of game development.
• He doesnt blog, but this 2004 podcast is a good starting point.

Paul Tozour is a very smart AI programmer.

• Fixing Pathfinding Once and For All is a great read.