A couple of other items...
Having just returned from South Andros this week, I agree with all of the previously mentioned items. I can also add one item to the list that I am glad I brought and one that I wish I'd brought.
First, I am glad I brought my rain jacket. We didn't have rain any day I was there, but I still got soaked every morning on the way to the flats and every afternoon we returned...and when it gets rough, you'll be especially glad you brought it! I would say this is a "must have".
Second, I wish I brought some neoprene / waterproof socks. Something like SealSkinz, etc. I did a fair amount of wading on this trip and anything that can keep sand/gravel out of your wading boots would be worth bringing. I tried using tube socks and found that they don't dry out that fast and they don't really keep anything out.
I would have to especially agree to bring some sandels and maybe a very small amount of detergent. Bonefish "slime" is very hard to get out of your scrubs when it gets on you. It dries with a very heavy, flaky film. Sun gloves are a must have also, in addition to a hat that covers the tops of your ears...very painful to get burned there!
Hope that helps, good luck!