Nadav Manham from SeekingAlpha posted such a simple but profound thought on when companies can grow without capital (The Tyranny of Corporate Capital Allocation: Who's Really the Investor?)
I can think of only three exceptions to this rule. One is companies like eBay that benefit from network effects--once they get their mousetrap going, it grows without their having to add more capital to it. Another is companies like Dell in its heyday, who have such good working capital dynamics that their customers essentially provide the capital needed to grow. The third is companies that can simply raise prices year in and year out, like newspapers once upon a time.
Simple and elegant.