Orafans hosts a number of high-volume forums for various Oracle topics. IOUG-A's Oracle discussion forum. You can subscribe to Quest Software's newsletter as well as browse previous issues on this page. Ixora's monthly newsletter primarily contains tuning tips and information on Oracle internals. Previous issues are available online.
All issues are available on the Web, subscription to the printed version is also free.
Oracle Professional is a monthly newsletter. You can find free material from it on this page. You can search or browse its archives on Intelligent Enterprise's site. Xephon's monthly Oracle journal. Old issues are freely available online.