I have explained four Dialogflow integrations on this website till date.
I personally think Twitter chatbots running on top of Dialogflow have great potential. But I think the conversation interface on Twitter is a bit limited.
You can read more about the Twitter integration here.
The Skype integration I have demonstrated is quite limited. So it is quite a basic article, but it should get you started.
Interestingly, there are no tutorials online which explain how to integrate Chatfuel and Dialogflow which also understand how session based contexts work in Dialogflow. If you have already created a Chatfuel bot and would like to add Dialogflow's AI capabilities to make it smarter, you can check out my tutorial.
The web integration with Dialogflow is the richest in terms of potential (and already implemented) functionality. Since I have particular interest in this domain, I have written about it quite a bit on this site. I will probably combine all of these into one big article someday, but for now the one which comes closest to being a reference is my article discussing the basics of rich webchats using Dialogflow.