Using PYTHON, JAVASCRIPT, C#, RUBY or other programming language?
I think almost none.
LISK currently is on trying to do this, but LISK only support javascript and they will release their SDK in Q1/2018.
While NEBLIO will release their API (in Q1/2018 too) that support variety of programming language such as Python, Go, JS, Ruby, .NET, Java, Node.js .
If this really happen and successful. NEBLIO would be the first "working" blockchain DAPPS that support variety of programming language...
Please correct me if i'm wrong.
If they can pull their goal of restful API's, i can see this gaining a lot of traction next year with developers