BigSteve, your example should include a dynamic timer to voice each user in a delay, or else you're running the risk of mode flood. Let's say lots of nick joins in at once or at the same time...the client that runs the code will be doomed without some sort of protection.

on @*:join:#:{
  $+(.timer,autov,#,$network,$nick) 1 5 mode # +v $nick - $&
    $(|) msg # $nick has been auto voiced. Hello and Welcome to # $nick $+ .
}

P.S. There is yet a /pvoice command that may be useful too.