There are many ways recurring payments can be implemented with the existing protocol. Here are three off the top of my head:
1. Use a third-party wallet like Coinbase and grant direct-debit permission to the service provider;
The goal was to avoid solutions that lock you up to specific services. We don't want a situation where you need a coinbase account to subscribe to the New York Times and a Bitpay account to pay your rent.
2. Receive a notification (email, wallet app, etc.) that a bill is due and pay it as a standard bitcoin payment;
Yes email is possible, but adds unneccessary steps. I don't get my regular bills in the mail. They go directly to my e-bank, and I just need to verify them. Similarly a bitcoin client should be able to handle recurring payments all by itself.
My proposal consists of wallet notifications and regular bitcoin payments. But there are some propblems that you are not adressing, such as the price of BTC may have doubled since your last payment so your client can't know how much it needs to pay.
Fund a 1-of-2 wallet where both you and the service provider have signing authority.
Sure, that could be useful. But the point was to make a standard easy way to set this up. Click a link and be done with it. I want a standard way to set up recurring payments so that all web sites could easily set up bitcoin subscriptions. This suggestion could be part of it if neccessary, but it's not solving the problem I'm talking about.
the OP started off taking about recurring payments then meandered off into th direction of explaining addressbooks.
Sorry if I was a bit unclear. I'm not necessarily talking about an adress book in the usual sense, more of a database of all the services you subscribe to. This is quite close to an adress book though since it's just a list of recipients you do regular payments to. I'm also talking about how to make the best use of this database to make the user experience as good as possible.
To make my self short, my suggestion consists of three things:
1. A database of recipients with standardized entries (recipient name, service info, payment info, adress seed, a link so the client can automatically look up info that changes with time). We need a standard for this so that all clients are compatible with all subscription based services.
2. A standard way to easily add entries to the database. I should be able to go to a subscription based web site, click "pay with bitcoin" and automatically download the neccessary info to my bitcoin client, and be able to handle all payments from the client from that point on.
3. A standard for web sites to provide information that changes with every payment, such as the price in BTC, so that a bitcoin client could look it up at the moment of payment.
I hope that was a lot clearer.
The reason I was talking about an adress book was that number 1 above is very close to it, and it may make sense to store recurring payment recipients in the same database as regular recipients (friends), but this is not necessary.