If you are looking to start a small business producing eggs or meat, and seek a quick turnaround time, quail are a good choice. The Coturnix Quail matures in about 6 weeks and should begin laying eggs at 8 weeks of age. The Chocolate variety is seen here.
Raising quail for sustainable eggs and meat is easy. If you live in an urban area that outlaws chickens, quail are a good alternative. Here's how to start quail farming. From FrugalChicken (Chicken Backyard Tutorials)