Blackblock has some custom items made for it by Skerit.
Even though these are full blocks & custom GUIs, they are fully compatible with vanilla clients.

Blocks

 Bark Mulch Carpet
Cardboard Box Chairs Chiseled Blocks
Chunkloader
Diamond Rail
Director Block
Engraver Block
Glimarine Bricks Gloncrete
Guild Chest
Gunpowder Block
Keyhole Block
Launchpad Block
Mailbox
Nether Chest
Pedestal
Speed Boost Block

Items

Bark
Cardboard
Chorus Cookie
Coffee Beans
Copper Nugget
Data Card
Diamond Shard
Empty Data Card
Gold Flecked Cookie Keys Mug Operation Cards Passports
Rusty Ingot
Rusty Nugget