I've really wanted to do this, like creating a <your_filename>.received_correctly_and_processed.txt file. Automatically removing the file after a while makes it sound even better.

The problem we often saw was that we were _so_ fast at picking and moving the file, that the user wouldn't ever see it, even when directly following the PUT with a DIR. It is one thing to see the transition from 'there' to "not there", but it kinda freaked them out that they never saw it at all. Like it had gone into the bit bucket. And our applications are named _somewhat_ differently...