Dr. Manabu Hagiwara, a mathematician at the Japanese Research Center for Information Security (RCIS), which is a part of the National Institute of Advanced Industrial Science and Technology (AIST), has released a free downloadable QR Code generator called QR-JAM MAKER ver.1.02 (screenshots below). It produces distinctive QR Codes with an image down a bar in the middle of the code. Different images can be selected from a menu and output can be small, medium or large, in .bmp or .jpg format. Color can also be selected although there are some limitations on the encoded string. I download and played with this for a while and had some difficulty reading the QR Codes.
I contacted Dr. Hagiwara and sent him an example of a code that would not scan with some readers. He told me that he had no difficulty in scanning the code and that the fault must be with the scanning software. I have reproduced that particular code below, please try to scan it and then leave a comment saying what you used and if the scan was succesful (or not).