I am usually extremely conservative with financial products, but this article that I read on Lifehacker today really caught my interest. Apparently, they have a new service where you can generate a one-time-use credit card number to use on sites where you might not feel comfortable using your permanent card number. The payment comes from your Paypal account. All of this is facilitated by a browser plug-in (IE or FF2).
I kind of like the idea behind this. I generally don't buy much online, except for big vendors, like Amazon. Something like this might make me more comfortable buying from a more diverse set of vendors. Of course, one would still have the basic concerns with unknown merchants (when will the item arrive, will it arrive as advertised, etc.), but the biggest gamble, that of whether your personal financial information is adequately secured, would be obviated.
Anyway, I haven't tried this technology, so cannot vouch for its quality; just wanted to point it out because I thought it was interesting.