The real question is what i wouldn't do with it. First off, though, i would give away half of my life to know the names of everyone. I would then write my own death in the deathnote so that i would die the ripe age of about two hundred years, because there isn't a rule saying that you can't write your own death and screw the pooches of the shinigami at the same time (i smell loop-hole 3nodding ). I would then kill off all political opposition so that i can take control of the crumbling remains of economic collapse and political gambits so that i can rebuild the world, become a hero, and finally die an old and happy man. I would probably go to Hell when its all over, but even Satan would say, "Damn, you're good".