Many searchers overlook the value of negative working capital. Everyone is hyper-aware of capex-intensity, but net working capital (NWC) is an afterthought for many.
Negative working capital means that your business collects cash from its customers before it pays its vendors. It's amazing, especially when compared to most businesses which require capital to grow and where fast growth can imperil liquidity.
In 2011 I co-founded a company called Venture Import, led by Peder Weidemann Egseth. We sold products on Groupon and instantly collected the cash, and then placed our orders with drop-shippers from China who we paid 30 days later. Our daily revenue peaked at ~$40,000, and we made a nice profit before Venture Import was discontinued due to its extreme channel concentration.