Lock-UnMatic tells you which processes on your Mac are currently using your files. The application runs only on OS X.
PADEdit is a free application which lets you view and modify PAD-files (PrivatAbrechnung Digital). The application runs on Windows, OS X and Linux.
Task Till Dawn is a free task scheduler which can execute your repetitive tasks (i.e. open files or applications) at specified times or intervals.
The application runs on Windows and OS X.
Sourcecodes of my libraries.