Being able to assert your identity online is problematical on good days and impossible on most. Having the ability to create and confirm your online identity is a subject close to what little heart I have. Getting your computer hacked and having someone using your identity from your email server to cause pain to you and others is not a thing you want to have happen. Believe me, it is next to impossible to track these folks down. Just check your spam folder.
There are a lot of really bright folks working on online ID projects to create a framework that will allow you to create, confirm, and manage your online identity. There is a new player on the horizon that may provide a method for a secure verifiable online identity system.
DomainKeys Identified Mail DKIM
While this is an email project, when you think about it, email is probably the most significant communication used. Having folks I communicate with able to confirm that it is me, and conversely being able to confirm your identity, is a very good thing. This is something to keep your eyes on.