Floating plants such as Limnobia levigatum, Riccia fluitans, and even Java Moss, are good for fry and for skittish fish: fry are safer among and below these plants, and as many other fish are picked off from above by birds, this puts them at ease.
I've kept some floating plants. If you have a decently open-topped aquarium, these plants can make the tank really beautiful! I have 10 huge tiger lotus pads (from one bulb) on the surface of my 55 right now, and they look phenomenal from the bottom and top. I think there are a couple of pictures of them in my gallery if you're interested in seeing them.