How about SO?
- https://stackoverflow.com/questions/64856/senior-j2ee-interview-questions
- https://stackoverflow.com/questions/72183/any-good-interview-questions-to-ask-prospective-junior-java-developers
Check the resources at this site, it has a very good collection of sample questions and answers: http://www.j2eebrain.com/j2ee-interview-questions-answers