An example I found of a well done student portfolio can be found at the web address: http://www.angelfire.com/tx4/credentials/index.html. Even though this website is very well put together, there are still a few minor things I would change about it.
The layout of all the pages is very good. The color scheme that the author uses is very easy to read, and there is not a lot of scrolling involved on most of the pages, so that makes it easier too.
One thing that I really like about this webpage is that there is not a lot of extraneous information. She gets straight to the point, and only gives us relevant information that we want to know.
One thing I would maybe change about this site is the navigation. Although there is a link back to the homepage on all of the sub pages, you can not go from sub page to sub page. Other than that, I think this page is very well put together.