Thought this might prove useful when designing our Kingdoms:
Here are the more popular building blocks and their 'blast resistance' (general strength vs Creepers / TNT)
Blast Resistance 1 or lower:
Snow Block
Blast Resistance 1 - 2:
Glowstone
Blast Resistance 2 - 2.5:
Dirt
Sand
Netherrack
Blast Resistance 3:
Clay
Gravel
Blast Reistance 4:
Sandstone
Blast Reistance 15:
Lapis Lazulini Block
Wooden Plank
Blast Resistance 30:
Brick Block
Cobblestone
Diamond Block
Gold Block
Iron Block
Moss Stone
Stone
Blast Resistance 6,000:
Obsidian