Hmm Silk Road did 22 million dollars of sales last year, probably will triple that this year. Bitcoin store did about $500,000 worth of sales in March. Bitpay has about 6000 merchants that use their service and did a few million in sales also in March.
I can buy just about anything I want online with Bitcoins with very low fees from anywhere in the world. Try that with your gold and silver.
Disclaimer: I own gold and silver, but its not a very good currency especially in this global commerce system we have.