A few links, and ideas for putting this practice into perspective. This is an excellent place to start since the Merkaba practice strengthens your energy body and will begin to expand your dimensional awareness, but what can you do with a sweet energy body?
This is a site sharing Lucid Dreaming techniques. Learn to be fully conscious in your dreams, and use this time wisely as a training ground for your godlike creative potential. Also, this site has a great focus on how to integrate shadow memory (dream memory) into the physical brain. Your experiences during and just after the Merkaba meditation are often more vast than your physical brain can handle, and fade suddenly and completely, much like the memory of a dream just after awakening. Use this site as a great next step.
This site shares Astral Travel techniques. It will guide you, if you are ready, to let go of the body, and begin to explore God's creation, and our identity as consciousness, leaving the body behind. You may want to do this sooner than later. Typically people discover it at literally the last minute -- of their lives -- and this makes death quite traumatic. Master these techniques, master your life and identity, and I'll see you very soon.
I mentioned Bob on the front page of this site. He's a great being and teacher. I recommend taking any class from him. He has a very special emphasis on a pranic-breathing initiation called Rebirthing. Check him out!