On my board, I have two issues that make me want to make the left & right columns invisible UNTIL the user logs in -- at which point they will be visible unless otherwise specified in the user preferences. I'd like to suggest this as an option for the following reasons:
(a) Some boards, like ours, are entirely private, and it is uncomfortable for users to have their usernames (top posters and who's online), topic titles, and shout box entries visible "to the world."
(b) Blind people with screen readers have troubles with the shout box. Apparently, the screen reader gets stuck on the shout box -- which prevents them from being able to tell where to log in. After they log in, of course, their preferences can be set to hide the left and right columns, and they don't have further problems.
I patched my site to remove the left & right columns for anonymous users, but hopefully this can be an option for the next version.
It would also be nice, in the spirit of confidentiality, to be able to disable the calendar for anonymous users.
Shane