If you are searching for some presents under the Christmas tree, you might want to consider following Oracle APEX books:
-) Oracle APEX Best Practices by Alex Nuijten, Iloon Ellen-Wolff, Learco Brizzi
This book was published a month ago. I was one of the reviewers and believe it's a nice collection of best practices that are now used in the APEX community. One of my favourite chapters in the book is chapter 2 "Leveraging the Database". It's not 100% APEX as such, but if you know how to write your queries (by understanding analytical functions, rollup, pipelined functions, etc.) you can get so much more out of your (interactive) reports in APEX.
-) Expert Oracle Application Express Plugins by Martin Giffy D'Souza
This book is almost a year old, but it's still a great resource if you want to build Oracle APEX plugins.
Martin explains very well the different plugin types and shows how to create them. I like the way he wrote the book as he also explains the business need for the different plugins.
-) Expert Oracle Application Express by Dietmar Aust, Martin Giffy D'Souza, Doug Gault, Dimitri Gielis, Roel Hartman, Michael Hichwa, Sharon Kennedy, Denes Kubicek, Raj Mattamal, Dan McGhan, Francis Mignault, Anton Nielsen, John Scott
More than a year old, but still a great source as so many different authors wrote about their expertise, so you get a big variety of topics. The royalties of the book also go to a good cause.
There are many other Oracle APEX books out there; from beginner to advanced.
Update: Packt is pleased to announce a special eBook offer – stock your reader this Christmas! During this celebration, you can buy two or more Packt eBook's of your choice for just $5.
Merry Christmas & Happy holidays.