I should have gotten some sleep before posting 
Sorry for resurrecting an old thread but I think this is not that stupid after all (not an elegant solution either, I admit).
As far as I understand, an implementation of niko's solution would be to maintain a list of 50 addresses of 0.01 BTC in each one of them (generated at home), and give the required number
of them in the form of QR codes to the seller (who typically is a brick-and-mortar with internet connection) . Assuming that
1. there are no problems with network fees
and
2. rounding error of <1$ is acceptable to either the seller and the buyer
this would work nicely
Let's make some numbers on this solution as an example:
1- Let's say I want to move on the street with my wallet fill with 100$ in bitcoin (whatever is the exchange rate that day) for my day to day usage.
2- This translated to bitcoins will mean I'll need to have enough addresses with me to create transactions that can go as high as 100$ and as low as 10 cents (we don't want to give away too much change on every transaction)
3- The total amount of addresses will be 1000
This is possible but I imagine the fees that go into creating the daily wallet (or every time you have to get another 100$ for the bitcoin ATM) will not be trivial. In addition, the size of each transaction combining several addresses into one payment means there will be a lot of QR codes sent and waiting a long time for the camera to recognize all of them (up to 1000 addresses in one transaction to pay something of 100$).