So far we don't have much trouble pricing goods in Bitcoin. But what happens when down the road, Bitcoins gain more value and we have to use the smaller decimal places? The average shopper will not want to see prices such as 0.00005 BTC, or 5x10^-5. I am proposing a solution using colors of the rainbow, ROYGBIV (plus black and white):

http://imgur.com/m0TutSo a car could be priced in "black" coins (standard BTC) while snack foods could be priced in, say, "yellow" coins (5 yellow coins = .005 BTC, equivalent to .005 black coins). Then clients could be configured to allow users which color they want to view their balance in. That way average users never have to deal with ugly decimals.

An example: suppose I own 0.03 BTC and I want to buy a .005 BTC snack item. The seller can choose to show the snack as 5 yellow coins instead of .005 BTC. Then I can say "hey, this seller is displaying the cost in yellow coins" and change my client to display my balance in yellow coins (0.03 BTC = 30 yellow coins). It just makes the math easier for people who are not mathematically inclined.