I think extension methods in C# are basically a way to work around the fact that you can't just stick a method on the prototype like you can in Javascript. I also like the C# solution, actually, I just love C#. It's a great "daily driver" language in my book.

If you took the function bind syntax to its natural extreme, you end up with a model like Python or Nim, where all instance methods accept their "this" as a first parameter, and "a.call(b)" is equivalent to "call(a, b)". Personally I always thought that was a particularly elegant way of implementing instance methods, because it doesn't require inheritance or modifying the original type.

In Nim it even lets you do some very interesting method chaining to replace nested calls, like "toInt(sqrt(toFloat(num)))" can be equivalently written "num.toFloat.sqrt.toInt"