Here are a few professional or organizational webistes that I have worked on in the past. If there is no link, odds are that the page has been changed since I used to work on it and I have not created a separate copy for demo uses.
WASS - Web-based Advising Scheduling System - my senior design project. Since this code technically belongs to the University, there's no demo username/password and I will only give this out to prospective employers. This site was put together in a real hurry - only about six weeks of 10-hour-a-week during the development phase and a very short testing & bug-hunting phase. The CEAS Advising & Admissions office has been using this application during Summer, 2006 as their primary scheduling system. Source code can be made available to prospective employers.
Spectrum Printers, Inc. - I didn't design the layout, but the entire code was reworked in my years at Spectrum for a PHP template system and everything. Source code can be made available at request but it is copyrighted by Spectrum Printers, Inc.
The Residence Hall Association - This actually isn't my site anymore, but I'll get online an old copy of the one I wrote.
MORHA 2004 Conference - Casey Hunt made the original design, but I made it a bit better, and I wrote the whole registration system for it. This site has since been moved for future conferences, but I'll put online a copy of the site that I did eventually.