You could 'buy' asset protection from an ex-wife, if you stored your wealth in encrypted bitcoins.
Incidentally that's exactly what I was joking about with my wife yesterday evening
On topic: everything you can buy online might be easier for some people to buy with Bitcoins because other forms of online payment are not available to them. For example: not everybody on the world has a bank account or may be able to get a credit card.
Private sellers can just accept Bitcoins easily for their products or services without having to worry about credit card agreements, charge-back risks or similar. Bitcoin is simply payment between two consenting peers.
As for specific kinds of products or services: anything credit card companies don't want to be involved with, hence denying people to pay for it via credit card. For example donations to WikiLeaks or buying Bitcoins (although that might be a bad example of something that is better bought with BTC
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