Seems like we need a good way to pay for things in real stores

[michaelmclees]

Would this work?  Set up a service wherein people create accounts and deposit BTC, like a bank.  They submit two things to the service.  A PIN of their choosing and a scan of their fingerprint.

Merchants have a register and a fingerprint scanner than can access the bank.  If sale price is 1BTC, you simply key in your PIN (so the service doesn't need to search all fingerprints in the database, only those with that same PIN) and scan your fingerprint.  When the system matches the fingerprint to the PIN, they send the BTC to the merchant.  Now you have a transaction with no cash and no card.  Only a number in the buyer's head and a finger on his hand.

[RodeoX]

I like parts of your idea. Avoiding the need to see the address is helpful. But requiring retailers to buy a fingerprint reader may keep some away. And a lot of people will be against giving up a fingerprint.
I tested the idea with a reader I bought used. It was not easy to get working under Linux, But I did finally make a cool unlocking system for my laptop. At that point there was nothing to do but try breaking in. I'll be damned if I did not get in about 10min later. The solution? I dusted a fingerprint with graphite dust, then lifted it with tape and attached it to paper on my finger. That's it.  Way to easy to defeat.

[smooth]

The problem with this is that a fingerprint is not a private key, so this approach requires the private key be stored on some server somewhere.

A better approach is to store your private key on a smartphone.  Put a QR code sticker on customer side of the cash register (with the cash register's Bitcoin address) and scan it with your smartphone, enter the amount, and the phone sends the payment to the cash register.  Alternately you can have display on your side of the register showing a QR code with the address and amount, so you don't have to enter it.

For protection against loss or theft of the phone, you can have another copy of the private key somewhere.  If necessary, you use that other copy to transfer your BTC a new key, hopefully before someone finds and cracks your phone

Unfortunately Bitcoin doesn't really do "instant" payments, so there are some issues with this.  Search on the forum for "vending machine problem."

[smooth]

I was actually thinking of a banklike service. You send them the bitcoin, so you do not have to have your private key with you. Basicly it replaces the credit card with a number on it with your finger with a fingerprint on it.

Fingerprint readers might be cool but once you are bringing banks into it, Bitcoin offers nothing new.  The same thing could be done with a regular credit card.

Bitcoin uniquely offers the ability to transact electronically without banks. 

[DukeOfEarl]

I tested the idea with a reader I bought used. It was not easy to get working under Linux, But I did finally make a cool unlocking system for my laptop. At that point there was nothing to do but try breaking in. I'll be damned if I did not get in about 10min later. The solution? I dusted a fingerprint with graphite dust, then lifted it with tape and attached it to paper on my finger. That's it.  Way to easy to defeat.

I work in the banking industry and get fingerprinted regularly.  Might as well skip the fingerprint part, which would leave just a PIN protecting the bitcoins.