This site gives your free online tests and helps you build your resume. Tests are for older version, why bother when its free.
Oracle Certified Associate -- http://www.wiziq.com/tests/oca,
For DBA -- http://www.wiziq.com/tests/dba,
SQL -- http://www.wiziq.com/tests/search.aspx?qry=sql
This site gives you multiple tests which will help you prepare for OCA exams.
Not that great certifications but kind of ok to have certifications in different domains.