Neem is great. We use it a lot in India. It's one of what some people informally call super-plants or wonder-plants, some others being banana, coconut, and bamboo. All have various uses, for different parts of the plant, not just the obvious ones, e.g. in the case of banana, people in India eat the flowers and stems too, made into curries).

Edit: Also garlic, ha ha. What would we do without it, for both food and (informal) medical uses.