I just bought tickets to see the Magnetic Fields from TicketWeb which was... quick, intuitive, clever. An all-round well-designed e-commerce site. Shocking.
When I entered my details there was one of those little privacy checkboxes, except it wasn't. It let you choose whether you wanted least/more/most privacy depending on whether you wanted junk mail, only mail from TicketWeb with gig information and so on, or only critical info. Clever. (I went for 'more', so it works.)