Xhinker

We can use InArgument to pass values to workflow when an activity start executing, and use OutArgument to pass values out from an activity when it is finished. Check this. Now, we want to pass values to an activity when it IS executing. we can use bookmark to handle this job.
My custom ReadLine Activity:

Code in workflow host:

Result:

Check this for more info:
http://msdn.microsoft.com/en-us/library/dd489442(VS.100).aspx