JICHO  Just found it! Looks promising, I'm missing the possibility to scan barcodes with my iSight. Besides that it looks good, workings fine and best of all it has a iPhone App that has no problems with Amazon so the App will stay in the iTunes Store :)

I'm going to test it a little bit further.  
(Version 0.9.6)

ALKOFOX  Book Hunter is a very good application for those who don't want to spend money on other expensive book cataloging applications like Librarian Pro. The interface is extremely easy to use and is nice and clean. There are enough features to satisfy the average user it doesn't have some of the features Librarian Pro has, but for a free application this little application is a gem. One of my favorite features is the ability to connect to amazon and get the books info.

I would recommend that you try Book Hunter first before buying some other expensive application as it truly is a super little application".  
(Version 0.9.6)