user117: Anyone who has recently used one of the Bitcoin wallets on a mobile device (and some desktop  clients) will have seen a Bitcoin QR code. Clearly, QR codes allow for a succinct method for transferring complex information in a reliable and error-resistant manner.
Naturally, the most obvious use of a QR code is for encoding a payment request URI. However, are there any other benefits that QR codes can bring to Bitcoin beyond this? 
I'm thinking in terms of marketing, exotic transaction types that sort of thing.

user5: There was a thread on bitcointalk about creating a specification to encode additional data (besides the address) in QR codes. This would work with a key/value pair and it could be used for a lot of things. Here is an example for merchant/buyer interaction:

Merchant request for direct payment via bitcoin network.
Code:
btcpayment-request1: name=“My Bitcoin Inc.”; pubkey=1LGpwDU5djqsR1X14Tcass3y9fULTzxJq3; amount=300
Using this QR-code, the mobile phone knows enough to ask the user if
  they wish to pay 300 BTC to My Bitcoin, Inc. at the given bitcoin
  address.  Presumably the mobile phone has the ability to make bitcoin
  payments, either directly (a lightweight bitcoin client) or indirectly
  via a payment API such as this.


user278: If I recall correctly, a bitcoin transaction can be coded to require a password to access them. Therefore, you could make the QR codes a way to hold a bitcoin outside of a wallet.

user758: I believe QR will be to BTC what paper is to cash. I even registered long ago QRBitCoins.com (and others) and am now waiting for the right project to prompt some work. I thought I should tell people in case there is any interesting on-going project that would need a good QR domain.

user204: You can use also use the standard bitcoin URI QR codes to transfer bitcoin addresses from one application to another. For instance you can show your Instawallet.com bitcoin address as a QR code and drag it into the MultiBit send bitcoin screen. (www.multibit.org). It automatically parses it and creates an 'address book' entry with the bitcoin address and label 'Instawallet'.
Similarly, you can generate a bitcoin QR code with a bitcoin address and your name as a label in the MultiBit receive bitcoin screen, copy it and print it on the back of your business card. 

user217: You can use QR codes with Shamir's Secret Sharing for making secure backups of deterministic wallets: http://code.google.com/p/bccapi/wiki/ManagingLongPassphrases

user105: In terms of marketing, here is a very nice QR code that could be used for spreading the word about Bitcoin. It contains a link to bitcoin.org. See this thread on bitcointalk.org for more information. It was created by phelix at bitcoinx.com.


117: <p>Anyone who has recently used one of the Bitcoin wallets on a mobile device (and some <a href="http://multibit.org">desktop  clients</a>) will have seen a Bitcoin <a href="http://en.wikipedia.org/wiki/QR_code">QR code</a>. Clearly, QR codes allow for a succinct method for transferring complex information in a reliable and error-resistant manner.</p>

<p>Naturally, the most obvious use of a QR code is for encoding a payment request URI. However, are there any other benefits that QR codes can bring to Bitcoin beyond this? </p>

<p>I'm thinking in terms of marketing, exotic transaction types that sort of thing.</p>
 5: <p>There was a thread on <a href="https://bitcointalk.org/index.php?topic=2038.0" rel="nofollow">bitcointalk</a> about creating a specification to encode additional data (besides the address) in QR codes. This would work with a key/value pair and it could be used for a lot of things. Here is an example for merchant/buyer interaction:</p>

<blockquote>
  <p><strong>Merchant request for direct payment via bitcoin network.</strong></p>
  
  <p>Code:</p>
  
  <p><code>btcpayment-request1: name=“My Bitcoin Inc.”; pubkey=1LGpwDU5djqsR1X14Tcass3y9fULTzxJq3; amount=300</code></p>
  
  <p>Using this QR-code, the mobile phone knows enough to ask the user if
  they wish to pay 300 BTC to My Bitcoin, Inc. at the given bitcoin
  address.  Presumably the mobile phone has the ability to make bitcoin
  payments, either directly (a lightweight bitcoin client) or indirectly
  via a payment API such as this.</p>
</blockquote>
 278: <p>If I recall correctly, a bitcoin transaction can be coded to require a password to access them. Therefore, you could make the QR codes a way to hold a bitcoin outside of a wallet.</p>
 758: <p>I believe QR will be to BTC what paper is to cash. I even registered long ago QRBitCoins.com (and others) and am now waiting for the right project to prompt some work. I thought I should tell people in case there is any interesting on-going project that would need a good QR domain.</p>
 204: <p>You can use also use the standard bitcoin URI QR codes to transfer bitcoin addresses from one application to another. For instance you can show your Instawallet.com bitcoin address as a QR code and drag it into the MultiBit send bitcoin screen. (www.multibit.org). It automatically parses it and creates an 'address book' entry with the bitcoin address and label 'Instawallet'.</p>

<p>Similarly, you can generate a bitcoin QR code with a bitcoin address and your name as a label in the MultiBit receive bitcoin screen, copy it and print it on the back of your business card. </p>
 217: <p>You can use QR codes with Shamir's Secret Sharing for making secure backups of deterministic wallets: <a href="http://code.google.com/p/bccapi/wiki/ManagingLongPassphrases" rel="nofollow">http://code.google.com/p/bccapi/wiki/ManagingLongPassphrases</a></p>
 105: <p>In terms of marketing, here is a very nice QR code that could be used for spreading the word about Bitcoin. It contains a link to <a href="http://www.bitcoin.org" rel="nofollow noreferrer">bitcoin.org</a>. See <a href="https://bitcointalk.org/index.php?topic=30981.0" rel="nofollow noreferrer">this thread</a> on bitcointalk.org for more information. It was created by phelix at <a href="http://bitcoinx.com/" rel="nofollow noreferrer">bitcoinx.com</a>.</p>

<p><img src="https://i.stack.imgur.com/nm9rw.png" alt="Bitcoin Extreme QR code"></p>
