In online world with youtube becoming so popular several users have their own youtube channel to showcase their own videos. In your web application you may have your own youtube channel about review of an place/item etc. For drupal based web application we have a module that exactly does this. The module is youtubechannel.
There are situations where drupal you want to assign a particular role to a user after he/she has been registered for a period of time. This functionality might be needed for situations where you want a user to get permission to perform a particular task on your site.