Extending Personal Campaign Pages
He outlined the process we took to extend one of Civi's core features, personal campaign pages, to be associated with CiviEvents. It's a custom solution we developed for a client of ours, allowing them to track the registration of teams for charity races. We've contributed our patches back to the CiviCRM community, allowing others using the system to also implement the functionality.
You can read all the details in the full blog post on CiviCRM.org.