As a freelance graphic artist, I also needed such a site. Actually, it was even long overdue but I finally got around doing a very basic portfolio for the moment. One of the most important aspects of an online portfolio is to show the work done in just one page - rather than having thumbnails or slideshows which require more clicking and browsing. It should be right there layed-out in front of everyone as if all the sample designs are spread out on a table like playing cards. I went a step further and created the whole site as one page. I think it's much better that way, what do you think? Click here to view my portfolio. Comments and suggestions welcome!
UPDATE: Please don't forget to add to your favorites and join the community. Thanks!