The wealth-building power of compound interest will never cease to amaze me. It's a story of patience and attention to detail, where small differences in the short term add up to massive divergence over decades. In the end, the biggest winners don't always deliver the fattest share-price returns.

Let's take a closer look at retail giant Wal-Mart (NYSE:WMT). Sam Walton's empire pumped an outrageous $464 billion of revenue through its machinery last year thanks to the customer-attracting power of low prices. A world-class supply chain keeps margins low but positive, and the company produced $14 billion of free cash in 2012. Of that massive haul, $5 billion was pumped into dividend payments, and another $6.3 billion was spent on net share buybacks.

A decade earlier, Wal-Mart spent just $2.5 billion on dividends and buybacks combined.

What it all boils down to is one of the strongest dividend-boosting policies anywhere. Rising payouts have helped Wal-Mart investors keep pace with the Dow Jones Industrial Average (DJINDICES:^DJI) over the last decade and pull way ahead since 2008.

WMT Chart

WMT data by YCharts.

Just how generous are Wal-Mart's dividend raises compared to other income-friendly Dow stocks? This next chart might shock you:

WMT Dividend Chart

WMT Dividend data by YCharts.

Procter & Gamble and Johnson & Johnson are two of the steadiest cash machines in the consumer-facing world, and they're not shy about sharing their wealth with investors. Coca-Cola is often held up as an example of how to run a dividend program. No doubt all three of these Dow stocks can help you build a rock-solid retirement portfolio with plenty of income-generating power. All three currently sport stronger yields than Wal-Mart.

But the Waltons are doing their level best to change the standing in that yield race. If current payout-boosting trends continue for a few more years -- and I don't see why they wouldn't -- it won't be long before Wal-Mart's yield jumps past all of these worthy rivals.