Multiple cellphones for multiple occasions

Problem:
One cellphone doesn't fit every situation.

Missing Feature:
I've got more than one iPod and more than one computer. Why oh why won't my cell phone company take more of my money and let me have multiple phones? The cellular providers and mobile phone manufacturers are missing a golden opportunity. Just as I own different iPods for different occasions I can't be the only gadget geek who'd love to have multiple phones. My iPhone, say, when I'm traveling or at work. But how about a sporty little number for when I'm at the beach, or a sleek Vertu for when I'm at an awards show in my tux? I'd never give up my iPhone, but I'd love to have other phones in my mobile repertoire.