Did you know there was a Registry of US Government Publication Digtization Projects? Me neither. But there is, and you can both contribute your institutions projects and browse through the existing ones at http://www.gpoaccess.gov/legacy/registry/. There’s not a lot here, unfortunately, though I like what I do see.
You can do a simple keyword search with the site, or you can browse. I think I like the browsing page better; you can browse by project title, institution name, category of project, project status, and those projects which are searching for partners.
I browsed the “Natural Sciences & Mathematics” category and came up with eight listings including “Military Medical Periodicals” and “Southern Oregon Digital Archives”. Clicking on the View link takes you to an extensive information page including description, URL, administrative information, and technical information (file formats, etc.) Great stuff, I just wish there was more here.