Simple bash_completion file: pip, venv-* functions. (venv-functions details: https://gist.github.com/nicolasramy/6438236#file-bash_functions_python)

pip.sh

#!/bin/sh

_pip_completion() {
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    first="${COMP_WORDS[0]}"

    commands=$($first --help | awk '/Commands\:/,/General Options\:/' | \
               \grep -E -o "^\s{2}\w*" | tr -d ' ')
    opts=$($first --help | \grep -E -o "((-\w{1}|--(\w|-)*=?)){1,2}")


    if [ $COMP_CWORD == 1 ] ; then
        COMPREPLY=( $(compgen -W "${commands}" -- ${cur}) )
        return 0
    fi

    if [[ ${cur} == -* ]] ; then
        local command_opts=$($first $prev --help | \
                             \grep -E -o "((-\w{1}|--(\w|-)*=?)){1,2}")
        COMPREPLY=( $(compgen -W "${command_opts}" -- ${cur}) )
        return 0
    fi
}

complete -o default -F _pip_completion pip
complete -o default -F _pip_completion pip2
complete -o default -F _pip_completion pip3

venvs.sh

#!/bin/sh
 
_list_virtual_envs() {
  local choix selection
  case "$COMP_CWORD" in
    # On 1st parameter, list '~/.virtualenvs' folder
    1) 
      available_envs=$( ls ~/.virtualenvs/  )
      ;;
 
    *)
      words=()
      ;;
  esac
 
  # Create list choice
  selection=${COMP_WORDS[COMP_CWORD]}
  COMPREPLY=( $( compgen -W '$available_envs' -- $selection  ) )
}
 
complete -F _list_virtual_envs venv-activate
complete -F _list_virtual_envs venv-remove

You have to make it available in /etc/bash_completion.d/