The best thing I can come up with is online-delivered services from non-US (and ideally, non-developed financial system) countries, to other non-developed-financial-system countries. Like, a guy in Zimbabwe who wants to provide an online service to someone from PNG. Which is really a stretch to imagine.
They would have a lot to lose by ripping off customers, vs. a random seller on silkroad, so I'd feel comfortable up to a few thousand dollars.
I think I've actually bought something from Memorydealers before. I'm not sure of the relationship between bitcoinstore and Memorydealers. If they're the same entity, then I'd be fine up to $100k or so -- it's a real business.
My credit card issuer effectively acts as an escrow agent, and I love that fact when ordering from companies. It has saved me more than once, too.
So, selling prepaid cards online would be a particular niche, maybe, or other things which are cash-equivalent.
There's some countries where receiving pre-approved credit cards monthly in your inbox isn't the norm.