Adding type information to dynamically typed languages has become a "new feature" in those languages lately. Most solutions are based on type annotations that imposes programmers to explicitly add type information in the code, something that those programmers are not used to do.
LiveTyping uses a different approach. It lets the computer do the hard work of adding and maintaining type information without polluting the source code with it, showing types when the programmer needs it and using them to improve the tools.
Having type information in a dynamically typed language helps in the accuracy of tools such as code completion, automatic refactorings, and many others.
LiveTyping is implemented in Smalltalk and it's been in production for more than five years. A Ruby prototype has been developed also.