I added some references of sites using bookalizer. A large Austrian bank was using the service for a few days as far as I can see out of the log files. But suddenly the log entries disappeared. What a pitty ... that would have been a nice reference ...

I saw in the web that some people isn't using the scripts in a correct way. They pass "undefined" as amazon tag to the service. This makes no sense although the link is working. I fixed this by replacing "undefined" by the amazon tag that is bound to the good cause. I think that's fair.