Something we've always prided ourselves on is just how extendable Gravity Forms is. From the very beginning we provided hooks and filters to customize Gravity Forms and its behavior and that library of available hooks and filters has grown and grown over the years.
With the introduction of both the Add-On Framework and the API we've positioned Gravity Forms as a great platform to build on top of. Just like Gravity Forms builds on top of WordPress, these tools can be leveraged to build incredible applications on top of Gravity Forms.
Gravity Forms programmer Steve Henty has put together a fantastic introductory tutorial on Gravity Forms as a Platform that we highly recommend you check out right here!
Gravity Forms features and capabilities from both a user and developer standpoint are going to continue to mature and evolve. We can't wait to see how developers take advantage of them. We also can't wait to introduce some of the things we've been doing with them. Enjoy!