Daniel Chudnov has made a prototype of a system for dynamically inserting links to local OpenURL services in web pages. It requires the user to have an appropriate bookmarklet - selectable from a list, similar to a LibraryLookup bookmarklet - plus a hidden link in each web page that can be transformed when the bookmarklet script is run:
<a name="OPENURL_DATA" rel="alternate" title="OpenURL"></a>
(where OPENURL_DATA is the data that would normally be in an OpenURL link).
I've added the appropriate code to HubMed's abstract pages (eg this one), to allow the bookmarklets to insert links, and will also submit a change so that the bookmarklets should work properly in Safari.