Learn about cryptographic escrow!  Actual "How It Works" text from my escrow utility available at https://casascius.com/btcaddress-alpha.zip


How Three-Party Cryptographic Escrow Works

Escrow allows two people to transact in Bitcoin while leaving their funds visible to everybody and accessible to nobody until somebody releases them.  It allows the payer or the payee to release funds to one another, and also lets a third person decide for them if the two can't agree.  The third person never has access to take the funds, and is only needed to release the funds if the original two can't agree who gets them.  Whoever gets a copy of all three "invitations" gets access to the funds....