Back to the main customer service line. Same results. No way to send an e-mail. I asked to speak to a supervisor. The supervisor says: "No e-mail." I ask how customers can make suggestions for improved service. She offers a snail-mail address.

Back to interactive services. I ask to speak to a supervisor there. A gentleman explains there is no enterprise mailbox address for online customers either - but maybe he could get authorization to give out his e-mail address or a colleague's. Long delay. Long delay. Long delay. I feel myself slowly changing from Don Quixote into Captain Ahab. He finally returns. He has an e-mail address for another supervisor. We double-check to make sure it's accurate.

I immediately send my memo. It gets bounced. I wait 24 hours. I try again. Nada. Nothing. Bubkes. When you've got a lemon, make lemonade. I decide to salvage my wasted time by writing this column.

But what's the big idea? Could it really be worth $50 million a year? You be the judge: My charge card company should offer an online expense report form that allows individuals like me to drag and drop individual expense items into a coherent, time-stamped and authenticated document that can be securely e-mailed to one's clients. The digital document would look and feel professional; you could send it either from your own address or from the card company's site. You could store the forms on your own machine or with the company or both.

Privacy concerns? Security? Come on! Do you really care who gets access to your expenses? Only a celebrity or a CEO who flies around in a Gulfstream V needs be wary of this service. After all, the charge card number can be appropriately masked.

Yes, I know about Quicken and other expense management software. But frankly, it would be faster, easier and simpler if I could just do everything online. Would I pay $29.95 a year to be able to prepare and send expenses this way? Cheerfully! Would I spend $50 a year to prepare, send and back up my expenses this way? You bet!

Do the maths. How many sole proprietors, freelance consultants and individuals - inside companies and out - are targets for this kind of service? My bet is, easily 1.5 million to 2.5 million cardholders and small businesses. A simple query to online users would help gauge global interest.

The bottom line? I can't give Amex a $50 million idea for free. Whether you like my idea or not is beside the point. The point is, your customers can and should be a dynamic source of ongoing innovation and inspiration for your organization. If you don't have a virtual suggestion box for them, you should. If you don't, don't be surprised when your smartest customers give their best ideas to your fiercest competitors.

Michael Schrage is codirector of the MIT Media Lab's eMarkets Initiative. He can be reached at schrage@media.mit.edu