Note: You can see videos of these features in action on NS Web Solutions' case study page for this project.
Update: Some of the code for these features is available on GitHub. See my comment below.
CiviCRM offers an incredible set of features straight out of the box. At NS Web Solutions we're sometimes asked to provide a CRM system with some pretty unique features, and we've found that by relying on CiviCRM's wide array of hooks and customization features, there's a lot that can be done.
We recently completed a project for a client that conducts many events per year in which all participants are fully sponsored to attend, including airfare, airport pickup, hotel accommodations, and meals. To complicate the equation, not all participants are given the same package; variations include hotel room type, in-room amenities, class of travel, length of stay, type of airport pickup, and more.
Seemlessly integrating all this data into CiviCRM was critical. We built a custom Drupal module implementing CiviCRM's wide array of hooks, in addition to a number of custom data fields, to achieve this.