Explore Entertainment

Information Sites

Gamedev.net - The best game development community I've found on the internet
Gamasutra - Lots of great information here too
Procedural Content Generation Wiki - Lots of general info on different PCG techniques

Blogs

Procedural World blog - An impressive one-man project to create a procedural world
John Whingham's blog - One man creating a whole universe procedurally

Games

Terraria - Open world sandbox action-adventure game; probably my favorite game of all time!
Dwarf Fortress - Incredibly deep sandbox-simulation game. Strike the earth!
Minecraft - Open world sandbox game