In front of me at work sits a Dell (DELL) computer running mostly Microsoft (MSFT) programs. In my bag is an Apple (AAPL) notebook. A good portion of my time on either is spent tracking down facts using Google (GOOG) search and trolling through stock data on Yahoo (YHOO) . The new, aluminum Apple replaces a plastic one, which I ll likely sell this weekend through eBay (EBAY) .

These six companies are so prominent I ll bet many readers, like me, use products or services made by all of them. They re no longer wunderkinds. Microsoft and Apple were founded when Gerald Ford was in the White House. Google is the size of John Deere (DE), Charles Schwab (SCHW), Nike (NKE), Fedex (FDX) and Costco (COST) combined. The best of them are slowing; Apple and Google this week said profits grew last quarter, but by a much smaller percentage than a year ago. Some are arguably past their prime; Microsoft and eBay this week said profits have recently shrank.

Remarkably, these aging tech giants sit on a combined $70 billion in excess cash, but only one, Microsoft, sees fit to pay a dividend. Consider that a year ago shares of these companies fetched a collective $730 billion, but today they sell for $377 billion. (That s a 48% drop, 10 percentage points more than the broad market suffered.) Their cash, then, is equal to 18% of their stock market value. That s neither normal nor wise.

The average company has no idle cash. Companies in the S&P 500 index, which represent three-quarters of America s stock market value, sell for a combined $7.6 trillion. They carry $3.3 trillion in long-term debt, after subtracting cash. It s an ambitious amount, and a few companies are dangerously burdened, but most have simply taken advantage of cheap loans; 10-year investment-grade corporate bonds yield 5.3%.

I d applaud these six companies if they were merely debt-free, or if they held small pots of cash out of caution. But eBay today could afford a one-time, 24% dividend. Apple could pay 31%. Dell, 33%. Or, each could afford a market-average yield for at least a decade.

Why the hoarding? The cash isn t for funding new products. A year s worth of research costs these companies 4% of their market values, on average, and is more than paid for out of operating profit. Some of the money might go to retire stock, but repurchases have slowed of late (even though shares have presumably become a better deal).

No, I m guessing these companies managers are eyeing their slowing growth and hanging onto cash with the thought of buying other businesses. They re smart people, after all, so their returns should beat those that stockholders could achieve with the same cash, right?

No small irony: You can search for it through Google Scholar

Nearly a year ago I wrote that Microsoft stockholders should be steamed. Management had offered a sum for Yahoo that valued it at three times Microsoft s own price/earnings ratio. As mad as that seemed, Yahoo s response was madder. It declined, and the stock has since lost 60%. A near disaster like that for Microsoft makes clear why grown-up companies should be conduits of profits to stockholders, not creative sandboxes stuffed with cash.

Dividends might sound old-fashioned to Internet visionaries. Stocks over the past two decades, after all, yielded just 2.2%. But that s half their two-century average, and it s mostly due to a bubbling-up of prices (including ones for these companies), not a sudden change in how investors profit from stocks. Throughout the history of stocks, reinvested dividends have formed the bulk of long-term returns, and gains just a sliver. It s time for these six tech giants to remember why those things investors buy are called shares. Stockholders deserve their share of the cash before it is squandered.