Are you teaching or are you student teaching? If you're student teaching, make sure you don't do anything that'll get under the district's skin -- your cooperating teacher has enough problems!
Does your district use course-management software (i.e. Blackboard, WebCT or ANGEL)? If so, you could have students blog, gather work and converse in discussion forums all within the auspices of an online class (and behind a password). I believe all three companies now offer e-portfolio software as well.
If you really do want your kids publishing to the big, mean world, I don't see any age requirements in the terms of service at
Blogger.
The overanxious IT guy in me says: "What a great chance to introduce these young minds to web design! Get everybody using Mozilla Composer!"
The burnt, frustrated teacher in me says: "God. I admire your gusto, but my kids are 18 and still can't spell 'won't.'"
I had a prospective teacher visiting the classroom the other day, and while I was helping a student with a worksheet, I overheard this conversation:
"Yo. How you spell 'won't'? W-o-u-n-t?"
"Nah. W-o-n-t. Won't."
"For real? I'm gonna ask that white woman."
So it goes.