I have just noticed that OTN has now an Oracle 10g Book Center. The page lists Oracle books from Oracle Press, Apress, Elsevier Digital Press, O’Reilly & Associates, Prentice Hall Professional Technical Reference, Rampant, TechPress and Sams Publishing.
Each book has a direct link to Amazon.com and most of them have sample chapters for you to download. There is also a single page to download all sample book chapters.
Check out the Oracle 10g Book Center on OTN.