What additional benefits can QR codes bring to Bitcoin applications beyond payment requests? 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.
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.