10 Minute Mail gives you a temporary email address on demand. Good when you're forced to provide an email address for product registration or to deal with some other marketing-inspired blackmail. I suppose it's also useful for criminal activity.
Personally I have a yahoo.com address that is purely used for junk mail. That works fine; I set the spam filter to the highest setting and it still seems to work. Makes the marketing droids happy, they think it's worth something. If 10 minute mail really caught on then email traps would refuse to accept it.