URI Widget for cck

Hi,
I'm wondering if somebody has developed a URI widget for CCK? I think it would be an extension of the link module. Another option is to just have a text field with a URI filter rather than a URL filter. Does anybody have any pointers? I'm working on a project that will hopefully integrate with the semantic web and we'd like to be able to link to external content using the extended URI protocols rather than URLs. IANA maintains a list of URI protocols.

thanks
Kehan