CONTENTdm is a good choice for consortia. I've seen it used well in Louisiana.
see http://www.oclc.org/services/brochures/11595LOUISCaseStudy.pdf
Some of the pros from the CONTENTdm website:
Collection Sharing
For many organizations, the drive to digitize collections is spurred by an interest in sharing unique collections with a wider audience. CONTENTdm technology and features make it easy to share collections and collaborate.
- Collections can be added to OCLC WorldCat so that your unique special collections become part of WorldCat's 60 million record global catalog. Descriptive metadata is added to WorldCat but collection owners retain complete control since individual items are served from your local server.
- CONTENTdm Servers support OAI harvesting by functioning as OAI repositories for customers who wish to make their metadata available for harvesting.
- CONTENTdm Multi-Site Server enables users to query multiple CONTENTdm Servers from a single search interface. Organizations can build and manage collections locally while allowing access to a wider range of users.
--EI