I am thinking of introducing a feature in one of my forum, where the users/visitors will be able to open a blog or one page profile under my domain name. Something like - www.mydomain.com/sarah .... which they can customize or do whatever they want to do. Is there any CMS or blogging platform that can take care of this? If there is, mind to share some details? Thanks!
Wordpress Multiuser aka Wordpress MU is what you're looking for. You can also have a subdomain installation i.e. sarah.mydomain.com