Umlaut is OpenURL link resolving middleware that adds functions and services to commercial link resolving software such as SFX.
About Umlaut - A gentle introduction to what Umlaut is and what it can do for you.
API documentation in rdoc format is available at: http://umlaut.rubyforge.org/api/
The umlaut project is hosted on rubyforge. You can see a project 'home' page (which is pretty much just this page) at: http://umlaut.rubyforge.org/
You can join the umlaut listserv at: http://rubyforge.org/mail/?group_id=4382