I am reading OCA Java SE 7 Programmer Cert guide by Manning. Recently noticed that it has a FB page (http://www.facebook.com/OCAJavaSE7), which has listed links to its articles posted on oracle.com, dzone.com and java.net. An interesting read.
If you've never taken an Oracle exam before, I advise you to buy a book anyway. Some questions can be tricky. You are paying $300 for the exam. If you don't pass on the first try, you are paying another $300. A single paid resource is less than 10% of this. You can get a book for $30-40. The enthuware mock exam software is $10.