I recently worked on porting over a website to Drupal that had several dynamic elements throughout the site depending on the IP address of the user. Different content could be shown depending on if the user was within a local network, a larger local network, or completely outside the network.

I just finished up a small project at work to create a basic resource management calendar to visualize and manage room and other asset reservations. The idea was to have a calendar that displayed reservations for various resources and allow privileged users the ability add reservations themselves. The existing system that was being used was a pain to work with and very time consuming - and I knew this could be done easily in Drupal 7. The solution could be extended to create a more general resource booking / room booking system.