Portfolio Time

One of the goals of this course is for the students and I to come up with a practical way to implement an online portfolio system for our school. I originally thought that a blog would be a perfect tool for such a creation -- online space that is easily editable. Now I think a blog is one piece -- perhaps the main piece -- but we'll need some sort of content storage or hosting situation. I like Ourmedia, and not just because I'm moderating for them. It's completely free for anyone to store just about anything (Of course, there are a few guidelines to follow, but they're fairly common sense.). Also, they're kid-friendly.
What are the other pieces to an online portfolio? I know that students need a place to reflect on their work (the blog), and a place to promote and or share what they've done (again, the blog) -- but I'm not sure what else is necessary for a successful portfolio, except for a portal where all the students' portfolios or blogs are listed for easy access.
What would you think is necessary for an online portfolio?