In such a market, anonymity is probably preferred.

Gift Cards. See things like http://www.swapagift.com/ And http://www.valutec.net/

Be careful though, under US law since 2001, you are probably committing a financial crime by doing anything that looks like anonymous digital cash.

Probably. But maybe less so in transactions that are not illegal.

Could be :)

Something like this could get merchants who don't traditionally accept credit to start