Mine

on *:START:{ set %minUsers 5 } 
on 1:INVITE:#:{ 
.timer $+ $chan 1 10 /ckUsers $chan 
} 
alias ckUsers { 
if ($chan == #HarpBot) || ($chan == #kor) || ($chan == #friendz) || ($chan == RSMarket2) { HALT }
  if $nick($1,0) < %minUsers { part $1 A minimum of %minUsers users are needed for $me to stay. } 
} 
on *:part: { if ($nick != $me) {
.timer $+ $chan 1 10 /ckUsers $chan 
}
}