The apt-get equivalent for Mac is brew
ruby -e “$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)”
once installed, you can
brew install imagamagick
It is not as comprehensive as apt-get in terms of packages— is what the internet says. I could install wget, apach2.4 and imagemagick easily. apt-get had problems installing imagemagick on LinuxMint14.