Marios asked me to elaborate a little on the Red Hat Certification Exams and my preparation.
I found the lab based exams much better than other multiple choice exams. It doesn’t matter if you do something using the command line, a gui tool, or if you write a program yourself to do the job. It’s real world simulation!
The preparation was self-study using the following:
- Exam objectives for RHCSA and RHCE
- RHCE Rapid Track Course Outline (RH299)
- Red Hat online skill assessment questionnaires
- Lots of RHEL documentation
- A few VMs to destroy while experimenting ;-)
No book covering RHEL6 existed while I was preparing, but I believe one is available now (ISBN 0321767950) and others are on their way (e.g. ISBN 0071765654).
I also recently discovered OpenRHCE by @texastwister, an effort to collaboratively prepare study materials to help candidates achieve Red Hat’s RHCE certification, under a CC license.
I found the journey of answering all the above quite a rewording experience. I have learned new things and I can definately troubleshoot SELinux issues faster than before ;-)
Don't fear the penguin 
Thanks Sotiris. I see that Official Docs are also under CC, good for RedHat!