Is there a promise-to-pay functionality with no escrow where a seller can set a bitcoin address for buyers to send promise-to-pay bitcoins. Once seller fulfills his promise, the buyers will confirm theirs: if 50% or more of the buyers confirm their promise, seller gets the money.
Example: An author promises to write a book if readers pay him N bitcoins. Once author's account has N or more promise-to-pay bitcoins author publishes book. Once 50% (this percentage can be adjusted) or more payees confirm the money goes to the author.