I have learned that Debian does not use the rc.local scripts, either under /etc or /etc/init.d .
The best thing to do is to create your own bash script, called anything you want, say, foo, which you then make available to run after everything else via,
sudo chmod 755 foo
sudo update-rc.d foo defaults 80
Scripts are best written compliant with the LSB specification:
http://wiki.debian.org/LSBInitScripts