Securing virtual territory for the kids

I was looking over all the domain names I have registered over the years, and remembered that I had registered full name domains for each of my children.  Someday, the logic went, they will want their own web sites, and they will be grateful that I had the foresight to grab these while I still could.

A sound idea.  But what about securing their username rights for web pages, web apps, and web services.  Should I grab AIM accounts for all of them?  Should I go ahead and register a Flickr name (i.e., Yahoo!) for each of the boys?  Gmail?

What do you think?