Full archives of Game Developer magazine
If you want to download all the PDFs to your current working directory:    wget -rH -nd -Dubm-us.net -Apdf http://gdcvault.com/gdmag

Edit: for the curious, the flags are:    -r recursively retrieve all the links on the page
    -H span hosts (default would stay with gdcvault.com only)
    -nd don't replicate directory hierarchy, just download the files to cwd
    -D only download from ubm-us.net
    -A pdf extensions only