Tom Pasley recently drew my attention to CrossRef's addition of a XML format parameter to their OpenURL resolver. Adding &format=xml to the OpenURL request retrieves bibliographic metadata in "unixref" format (for those who like this sort of thing, the XML schema is here). The biggest change is now the metadata lists more than one author for multi-author papers.
I tend to use JSON for my work now, so a common task is to convert XML data streams into JSON. I've modified my bioGUID OpenURL resolver to make use of the unixref format, which meant I had to write a XSLT file to convert unixref to JSON. If you're interested, you can grab a copy here. It's not pretty, but it seems to work OK.
For some years now I've relied on Marc Liyanage's excellent tool TestXSLT to develop XSLT files. If you have a Mac and work with XSLT, then I do yourself a favour and grab a copy of this free tool.