The Subject to this thread could just as aptly be called "Buying and selling amazon gift cards for bitUSD" (see the difference?)
Exchanges of goods and services in bitUSD or other bitAssets improve their utility, liquidity, and demand. So its more than just an on/off-ramp.
The full extension of this idea is to foster a marketplace for the exchange of all kinds of goods or services. This would encourage members of the community to be the early adopters in assuming the role of consumers and merchants using bitAsset currencies, in advance of external merchants making the transition. A dedicated marketplace tool, with supporting services like auction, escrow, feedback and reputation, could offer a number of benefits that I discuss further in the proposal "Could bitShares allow greater value exchange between users" here (see particularly Reply #7 for summary) - https://bitsharestalk.org/index.php?topic=11004.msg145078#msg145078
An alternative may to to partner with an external pre-built marketplace which could use bitAssets as the transactional currencies. However this separates the tools and reputation systems from bitShares.