I have a fondness for these things, I'm that way inclined and I recently took advantage for my daily communte time to listen to Rothbard's What Has Government Done to Our Money? (everyone should take the time to read it). It seems that there's quite the industry behind eCache (by which I mean "not very much", but it's still more than I expected).
eGold has existed for a long time and claims to have 35K 24-hour active accounts, which is tiny compared to VISA, but pretty shockly high otherwise considered. Then there's unlinQ, which converts eGold/eCache to virtual-credit cards (although "only available in fixed denominations, can't be reloaded or refunded" suggests that you loose a lot in the granularity since you generally can't pay for things with multiple cards).
eCache claims to have 310 grams of gold, which is about $7500 worth of backing. Again, hardly going to set the world on fire, but it's more than some guy in a basement somewhere. I have no hope that it will go anywhere, but it's nice cyberpunk porn.