invent something that benefits mankind

I would really like to do this. I read an article on a man inventing a retractable syringe. This is the kind of idea that i would have loved to make. Im not sure if they have been released in the US yet, but all the hospitals are going to use them for safety. This eliminates second-hand needles that some drug addicts use which spreads such horrible diseases such as AIDS. Now… to think of an idea.