It would be pretty difficult to think of any crypto-currency these days as a means of payment (and this is what their exchange-rates so unstable). Even so, it’s a possibility that can still be put to use — and here’s how.
The payment issues that crypto-currencies solve well are the speed of transactions, and the non-reversible nature of payments. These become crucial issues when there’s no inbuilt trust between buyer and seller. For example, let’s take the case of online auctions — where the seller is unwilling to ship the item to the buyer, until they’ve seen the buyer’s payment — while on the other hand, the buyer is reluctant to send payment while still uncertain if their item has shipped.
Here’s the workaround. Instead of paying in Bitcoin, or waiting on a bank transfer until shipping the item, buyers could make an advance Bitcoin payment (by placing the funds in escrow) and in the meantime, sending a bank transfer. The seller, once they see their balance has been credited with the Bitcoin advance, can then calmly dispatch the item, or begin work. Then, in a few days, when the bank transfer funds arrive, they can simply send the advance payment back by return. This all means that the volatility of Bitcoin needn’t become a business hiccup, but instead help things run more smoothly.
UPD from Vladimir Dubinin — that’s the place you need for servicing short-term loans in Bitcoin!