Hi all, other than those mentioned above, you also can try NAUI. I'm with NAUI :)
The National Association of Underwater Instructors (NAUI Worldwide) has been teaching the world to dive safely since 1959. As the largest non-profit and most respected dive training and certifying organization in the world, NAUI offers a full range of training programs from Skin Diver through Instructor Course Director, with dozens of specialty courses including Nitrox and Technical diving.
Diving with an underwater digital camera makes such a huge difference.
Sipadan was my first trip with my Nikon. It's an absolute must to have a camera to capture all the things you see as you may not see some of these creatures elsewhere in the world.
If you don't have one, no worries. You can always rent one at the resort and have them upload the pictures and burn onto a CD to take home :)
Fondest memory: The new friends that I've made in Sipadan are the type of friendships that you can keep. We are still in touch with one another though we live in Malaysia, Singapore, France, Portugal and Canada.
P.S. - Camera came in really handy as well for land shots!