Try getting Tom Kyte's books Expert one-on-one Oracle and Effective Oracle by Design. They're good intermediate-advanced level Oracle books that are well written by someone who knows the product well.
Additionally, get to know the data dictionary. If you have aspirations to be anything more than a 'tools guy' in the Oracle world the data dictionary is your friend. It's also much better than the one in SQL Server.
Finally, if you're moving to Oracle from a MS-Only world, get some background in unix and shell script programming. You will find this very useful when scripting automation infrastructure for Oracle systems, particularly if they sit on vanilla Unix installs.
There is any amount of legacy Oracle/Unix kit still in production and vanilla installs of Solaris, AIX or HP/UX tend to be much more spartan than Linux. In the Unix/Oracle world you can't necessarily rely on being able to install Perl or Python.
When you do have access to Perl or Python, get to know these as well. If you're into python, the best Oracle database interface library is cx_Oracle. I can't really vouch for any particular Perl infrastructure as I have never had occasion to use it for this type of work. CPAN is the canonical resource for add-on modules for Perl.
In the (relatively unlikely) event that you're working on an Oracle/Windows environment(Oracle on Linux is more widely used in low-end Oracle deployments), good Windows distributions of both Perl and Python can be downloaded from Activestate.