Another possible solution to the Myspace/Facebook problem is to have a school email address. I know in my second school, everyone was given a school email address. On the school website, you could access your school email address and email any teacher (or student if you had their email address). I think colleges do an similar thing, but this was a middle school.

Or, the school could make the teachers' work email address more public. For me, I learned the trick to email a teacher in my area, thus I can email any teacher. I have often communicated with teachers over email. But if the school made it possible for students to locate their teachers' email addresses, that would be a "safer" way to communicate beyond school hours.