i think this was true years ago, but now that the general public is internet aware, a billboard with B.com or Z.com would work just fine. In Asia they don't put the .com or .whatever on the ads, they just put the brand name and the general public know to search for that term.
Maybe, I find that people are still surprised when they need my email and it's just <firstname>@<lastname>.net and not @hotmail.com / @gmail.com or something like that.
