I am asking this question here because I could not think of a more appropriate place to ask it. What is the command to unzip a gz file? I'd like to look at some of the models on the model page but they are *.gz files.

To unpack .tar.gz files you can use the -z option on tar ...
   tar -z -xf archive.tar.gz

Rather than .tar.gz, these files are often given a .tgz suffix.

-Ken