Book Magic is a simple application that allows you to catalog the ebooks you have on your mac. You just need to select the directory where you have all your ebooks and the program will tell you the amount of titles you have, authors, series, file types, total number of ebooks, and duplicates, if any. The titles will appear on a list and you can change their file names, if you want. You can create a library catalog of your titles and save it as bookpedia xml, tab delimited, or CVS file.
Unfortunately, the program only allows you to enter one directory, so you will need to save all your ebooks in a single folder or create different libraries. Other tools include the ability to remove the id numbers added to ebook files by Bookstar, in case you have downloaded ebooks from there. The program also allows you change the configuration and format of author's name by adding spaces, commas or periods to the names.
In short, if you have multiple ebooks and you are looking for a simple tool to help you catalog them, Book Magic may work for you.