Need help developing an interactive job board

I am investigating the feasibility of developing a website to connect volunteers with non-profit organizations. The idea would be similar to [login to view URL] except individuals would "bid" to donate their time and expertise to projects posted by non-profit development organizations and field level programs. The website would need to be attractive with a user interface that is similar to something like [login to view URL] or globalgiving.org. Non-profit organizations would have the ability to develop a general profile that would be approved by our admin team. Once approved the non-profits would be able to post different projects which would have accompanying profiles that would explain the project need. Volunteers would also be able to set up profiles which would contain information about themselves, a profile photo, and a resume with information about their professional experience and educational background. There would need to be a rating system for the non-profits (where volunteers would rank the non-profit after working on a project with them) and also a rating system for the volunteers (where the non-profit would rate the volunteer). After a non-profit posts a project volunteers would be able to "offer their services". The non-profit could choose which volunteer they wanted to work with.