As you probably might know, you can ask your user to provide some information when launching the action.
This data is then stored inside the workflow. You can surface it by using the "edit item" activity and putting this value unto some SharePoint field, or for example send it in the e-mail and so on.
In the new release we will also display that data in the workflow history. Thanks to this new functionality you will be able to easily check what data the users have provided in the launch form.
You can see how it looks on the screen-shots from the beta version: