Tips to resolve Oracle Database Errors

I found this really good site called Oratip that lists every single Oracle Error, for Oracle datbase, SQL*Loader, RMAN etc.  There are over 18000 pages.  Every error gives you the error message, the cause of the error and the action you should take to resolve it.  Also you can enter comments (user posts) to ask questions about the oracle error, or leave your own tips for others. Very cool.