You know in bitcoin they have a standard payment form that fills in stuff automatically.. not just the payment address but also an expiry time for the payment... I don't know what BIP it is or the format... anyway, an upgraded version of that would be nice. The improved version would ideally be crypto neutral, so that other cryptocurrencies can adopt the same form. The requester form would specify the target currency and value (USD, EUR, CNY etc), along with the accepted currencies in the form.. this would allow for a mixed payment from the user and, thus, not requiring an exchange.
Maybe something like....
{
"seller-name": "TheBookShop.com",
"basket-id": "123456",
"basket-expiry": "2015-12-31 1355"
"product-title": "How Dash Overtook Bitcoin by dazman"
"target-currency": "USD",
"target-value": "9.99",
"accepted-cryptos": ["dash", "bitcoin", "nubits", "peercoin"]
"keywords": ["books"]
}