I just had some spare time and wrote a Script that extracts all translatable entries from a given Directory.
The Script is called LangBuilder and is attached to this post. It should work under Mac OS X or Linux with PHP installed. I wasn't able to test this on Windows as of now.
Extract the archive. The LangBuilder.php script is a command line PHP script. You'll need to set the executable permission bit (eg. chmod 0755 LangBuilder.php).
Open your shell and type:
LangBuilder.php module/dir pathto/outputfile.php
This will search the module/dir and all its sub-directories for translatable strings and write them to pathto/outputfile.php.
For help, just enter
I ran this script for the event_calendar module folder. Attached to this post, you'll find the auto-generated file (autocreated.php)
Hope that helps.
This script might be useful for all module developers. I should possibly provide it somewhere for download.