Which is the best way to create an online book database?

We intend to develop the project of an online children’s book catalogue. We need to classify the entries according to different categories: age, topic, author, etc. We will include the book cover, description and keywords. User should be able to search and sort items by title, author, date added, etc.
I have tried Alexandria, but it seems a bit complicated. I also tried WordPress, but it seems it does not handle categories very well. Also had a look at Joomla, couldn’t figure it out. Should we go to the expensive and complex Filemaker alternative? Is there any Content Manager System that would do the job?
We need something as simple as possible, even if we cannot have all the featrues.
One should be able to assign one book to more than one category, i.e. Author: Dahl, Roald; Title: The Twits; Topic: Humour, Hygiene, Family… ; Age: 8+
Thanks a lot!
Mauricio Paredes
President, IBBYChile (International Board on Books for Young People, Chile). www.ibby.org , www.ibbychile.cl
LibraryThing.com is great!
Is it better than www.reader2.com ?
Thanks a lot!