The stock market could tag on another 20 percent before valuations become a concern.

FORBES: Uncle Ben Wants You to Own Stocks

Firms tag all of their trades with a unique identifier for each trade by customer, by stock and time, among other things, Lime Brokerage CEO Jeff Wecker says.

FORBES: SEC To Say 'Tag, You're It'

If a customer likes 1 of the 400 sofas on Davidow's floor, he removes a tag from the item and scans it at a computer to see if it's in stock.

FORBES: Hurry Up And Wait