This was handy before oh-my-zsh but omz has functionality for this now that it's no longer necessary.

    pman()
    {
        man -t "${1}" | open -f -a /System/Applications/Preview.app
    }

I like using this in conjunction with pbcopy to quickly generate a random password at given length

    pwgen()
    {
        length=${1:-64}
        charlist='0-9a-zA-Z~!@#$%^&*()_+-=:";<>?,./'
        echo `cat /dev/random | tr -dc $charlist | head -c$length`
    }