My Cuckoo Marans, the "chocolate eggers" are laying now. Some Maran varieties are said to lay darker eggs than the Cuckoos, but I'm pretty happy with the shade that mine are producing. The color is just a perk, after all - it's the egg I'm after.
This is a photo of a Buff Orpington egg and a Cuckoo Maran egg.
My daughter was very disappointed that these weren't real chocolate eggs.