Member Rara Avis
Believe it or not, your suggestion and question are related - and have contradictory answers.
I "started" to impliment your suggestion about a month ago, when I began work on our new software (which was necessary because of changes in government legislation), even going so far as to set aside a number of fields in your Profile records to store favorite icon, favorite font, etcetera. The problem I ran into was that, for many of the people who frequent the forums, our software doesn't really know who they are until their first post of the day (or sesssion). By then, of course, it's a little late.
The new software (getting close) will have a "Login" function, which will open the door for a number of new features. For example, it might then be possible to have a "Who's On?" feature so we know who is here the same time we are. Or, of course, it might be possible to impliment your suggestion.
As for the private forums, like Adult, the answer is exactly the opposite. In many cases, where you are using persistent cookies, the software knows who you are the minute you hit the front page. In cases like that, it doesn't ask what I feel are stupid questions: "Are you really who I think you are?" Try deleting your cookies and then entering Adult - it will ask you to verify your identity then!