Oracle OLAP is the multi-dimension option for the Oracle Database that facilitates the storage of information in dimensional arrays or "cubes". Vlamis is recognized as the leading expert consulting firm on Oracle OLAP implementations. Oracle OLAP has numerous advantages in Data Warehousing implementations and is ideally suited as a "data warehouse accelerator" and analytics engine.
Dan and Chris from Vlamis Software Solutions co-authored the "bible" for Oracle OLAP from Oracle Press titled: Oracle Essbase & OLAP: The Guide to Oracle’s Multidimensional Solution
Here is a link to the McGraw Hill publisher's site. http://mhprofessional.com/product.php?isbn=0071621822
Here is a link to the Amazon.com site. http://www.amazon.com/Oracle-Essbase-OLAP-Multidimensional-Solution/dp/0071621822/ref=sr_1_1?ie=UTF8&qid=1299864809&sr=8-1
Here is a link for Oracle's OLAP page. http://www.oracle.com/us/products/database/options/olap/index.html