Game Extractor has had the ability to extract LEGO Digital Designer LIF files for a while, but since Game Extractor isn't very stable, I wrote my own LIF extractor in Python. The download contains the Python source file for use with a python interpreter, as well as Windows 32 bit and Windows 64 bit executables. Download LIF Extractor
GitHub
For those of you who will probably ignore the Readme.txt file entirely, here's the information on it:
You accept full responsibility for how you use this program.
This program is released under GNU GPLv3.
LIF Extractor is a command line utility for extracting the LIF files found in LEGO Digital Designer. It will extract all files contained inside the LIF archives, into folders adjacent to the archive it was called on. The LIFExtractor.py file requires a python installation to run. The executables found in the folders have no dependencies. Choose the proper folder for your operating system. The Python script has been tested to work on Python versions 2.7 through 3.2.
To extract LIF files, pass the path to the LIF files as command line arguments to the program. On Windows, this can be done by dragging and dropping the LIF files onto the LIFExtractor.exe icon in the explorer window.
This program was created to allow for interoperability with the LEGO Digital Designer formats. In order to properly read the LEGO Digital Designer formats, it is necessary to access the data contained with the LIF file archives.