If you’re curious to know what you can do with OTB and actually what people do with it, you can have a look at some presentations made this year.
These presentations show some research work using OTB, particularly in the special session on open source at IGARSS in Cape Town in July. The presentations are available here. They cover a wide range of topics, from information extraction (object counting, semantic coding) to learning (with a detailed implementation on Kohonen) and from map updating to GUI designing.
One other presentation done at Foss4g in Sydney in October is more general and provide some insights on the next evolutions of OTB.
If you have more examples of some interesting application, do not hesitate to let us know, we can feature them as well!