Kramnik could likely discover a cure for dandruff, if he'd only put his mind to it.
And Topalov...well, that's a rare genius. I would more expect him to revive fan dancing, bringing new rhythmic ideas to the craft.
As for Anand...I'd buy a used car from him. If there was a good warranty.
When he was four he could memorize all the countries their population and their capitals that's insane for a four year old