Remote flash, from above, is a great way to get a very good effect, as Scooty said. There's also specialized Macro Ring flash units that are awesome, but cost more than a quality Macro lens...lol.
I also agree, with using a plastic gray card for custom white balance. I've used white before, but most cameras, even newer ones, have a rough time with our reef lighting, and white doesn't always work out. To custom white balance, you'll need to take a pic of the white or gray card, IN your tank. Try and fill all or most of the frame with the card. Then you tell the camera to use that photo to custom white balance from.
You can also, with newer cameras, adjust the white balance and flash, to certain Kelvin ratings. Sometimes, this works better than using white or gray cards.
Never shoot at an angle, as this causes a lot of distortion, through the glass.
I shoot all of my pictures in Manual mode, though want to try some in Aperture priority. I rarely use a Tri-pod, but am using a DSLR and "fast" lenses. With some camera/lens combos, you can put the camera or lens directly against the glass, to steady the camera.
If you come to the meeting, bring your camera along!!