The leaves should not be composted or used as a mulch, because the toxin will persist. The nuts seems to have no effect on the people or squirrels that love them. Juglone does, however, seem to keep the earthworms away. There are black walnuts problems not related to the juglone toxin. Skin reactions, sometimes severe, may occur.
People can also be allergic to the pollen given off by the catkins in late spring.
Unless it is just a small seedling, removing the tree isn't a practical solution because the decaying roots will continue to give off juglone for years. First of all, use plants that are resistant to juglone. Some research has been done regarding the effect of black walnuts on other plants, but most of it involved field crops, not landscape plants. One of the most encouraging bits of information is that the effects of the toxin seem to be much less if the soil is heavily amended with organic matter. Apparently the bacteria in the compost help break down the juglone.