I just wanted to post a link to the blog platform that I have had students use in the past. Edublogs.org (and their companion site, Uniblogs.org) is free, uses an open source blog back end (WordPress), has scads of helpful support forum threads (many by students themselves), and gives them some free space to upload files.
The other nice thing is that there are "Pages" and "Posts." Posts scroll and are good for traditional blog posts. Pages are static and listed in a menu so we used them for portfolio materials.
Here are some examples of student projects from last semester:
http://rddandsecurity.uniblogs.org/
http://jjackson.edublogs.org/
http://kls66.uniblogs.org/
