The site should sell your organization's culture and mission. The site should sell careers, not just jobs.
Most potential applicants are interested in how they can grow with the organization.
The site should focus on your most important recruiting needs. Focus on either the openings you have a hard time filling, or those you fill the most often. Giving equal weight to every job posting only waters down your most critical needs. The site should have a way to establish a relationship with the visitor. Most passive job seekers will never visit your web site again.