find, tar, awk, and sed are not included in coreutils:

brew install coreutils findutils gnu-tar gawk gnu-sed

You can use brew search gnu to search for other formulas where the name contains gnu.

Formulas for other commands that are not installed by default:

brew install ack aspell dos2unix exiftool ffmpeg ghostscript iftop imagemagick lame multimarkdown netcat pandoc parallel pidof poppler pstree recode rename sox ssh-copy-id tmux tree watch wget xmlstarlet

I tried running compgen -c on Ubuntu and OS X VMs and running this:

comm -23 <(sort ubuntu) <(sort osx) | parallel -P10 brew info {} \> /dev/null 2\>\&1 \&\& echo {} | sort -u | tr '\n' ' '

There were surprisingly few formulas, but the formula names don't always match command names:

_lzma apg arping aspell dash dnsmasq dpkg duplicity enchant fribidi gcc gettext ghostscript gpg gs lesspipe logrotate lzma lzmainfo mawk mtools mtr netcat ntfs-3g pdftohtml pidof pkg-config pstree rename ssh-copy-id unlzma usbmuxd watch wget xz

According to the Homebrew terminology, we have the following definitions :

Cellar : All Kegs are installed here

Keg : The installation prefix of a Formula

Formula: The package definition

Homebrew installs to the Cellar it then symlinks some of the installation into /usr/local so that other programs can see what's going on.

As said in the comments, to list all packages previously installed on a backup drive you can do :

ls -1 /Volumes/*/usr/local/Cellar

If you want to have a better understanding of Homebrew paths, I recommend the reading of the following article : The Path to Homebrew.