http://www.oracle.com/technology/software/products/database/index.html?rssid=rss_otn_soft
For OLAP, Data Mining and Warehouse Builder you will need to download the database, client and Examples zip files. Look for the See All link on that page:

http://www.oracle.com/technology/software/products/database/oracle11g/111060_win32soft.html
All the documentation to support 11g is also available via OTN:
http://www.oracle.com/technology/documentation/database11gR1.html