Steven Phenix has compiled his list of the ten most important elements of a corporate web site:
1. Put a tab or link on the main page of your site saying "newsroom" or "pressroom" so reporters can immediately find it.
2. Give reporters a quick and obvious way to find your public relations person. Contact information should include direct office line, e-mail address, and in-meeting/after-hours/on-vacation options such as a cell phone number or pager.
Steven seems to have a pretty PR-centric view of corporate site design. I can think of at least five things that are more important, starting with a clear, concise description of your company's products and services that any normal human can understand. Still, his is a valuable list if you amend it 'most important PR elements of a corporate web site'.