ofxSpeech
https://github.com/latrokles/ofxSpeech

Speech recognition and synthesis is touted as the next-generation of user interfaces due to the fact that it can be hands-free and could potentially adapt to the high multitasking demands of today’s world.

ofxLibWebSockets
https://github.com/labatrockwell/ofxLibwebsockets

WebSockets is a relatively new and amazing way to open a socket over the internet. This allows for real-time communication with another application over the web, rather than polling for information. Primarily, WebSockets have been used only in web applications, but this add-on gives us the capability to extend it into rich processor-intensive applications.

ofxLeapMotion
https://github.com/ofTheo/ofxLeapMotion

This addon allows you to take tracking information from the LeapMotion controller to interact with your sketch. This is really interesting for the development of Natural User Interfaces similar to Minority Report.

ofxTransparentWindow
[vimeo=https://vimeo.com/15765520]
http://forum.openframeworks.cc/t/ofxtransparentwindow-osx-only/4811

This addon is rather old (4 years as of writing) but unlocks some really interesting possible interactions with other instances of OFapps. For example, it may be possible to push windows and objects on to a transparent layer on other computers. Instances of this are seen in science fiction movies and shows all the time, where digital collaboration happens seamlessly by swiping windows on to a colleague’s display. With the combination of ofxLeapMotion, this type of interaction would be possible

ofxARDrone
https://github.com/memo/ofxARDrone

I’m really excited about this add-on simply because I just recently purchased an AR.Drone 2.0 and I’m eager to control it programmatically. Using some of OF’s openCV or face tracking add-ons, this could be used to control a quad to track and follow people.

ofxCamaraLucida
https://github.com/chparsons/ofxCamaraLucida

I found this add-on interesting because Austin McCasland and I created a very primitive version of this to dynamically project flames on to objects on the floor of a fire pit last semester for a project. Had we known about this library, we could have avoided the hassle of building it ourselves. In either case, this add-on is very robust and could be used all sorts of interesting projection mapping such as using the RGB camera image to detect heart rate and projecting it directly on the person.