Here‘s an update of the COinS WordPress plugin. It fixes a couple of errors in the previous version (content of the
class attribute as pointed out by Eric and Alf, and encoding of the ampersands in the context object), and renames some of its internals to incorporate COinS terminology. Note: the file has a new name,
COinS_button.php instead of
openurl_button.php. If you’ve installed the earlier version, you should delete it when you install the new version; otherwise you’ll get both the old and the new buttons.
And here’s a sample COinS created by the plugin (again, you won’t see it unless you have an activating agent): 
The available fields are still the bare minimum to create a usable link for a journal article. It would be easy to keep adding fields: each one would take two lines of copy-and-pasted code. Just add the field to the form, and add a call to
addField() in the
show() function. If someone writes a nifty all-purpose AJAX-based OpenURL editor, it would be possible to plug it in here; it wouldn’t be that big a job. It would also be useful to be able to paste in, say, a MODS record (or the uri of one) and have it automatically generate the context object. Some validation would be nice. But I’ll have to get the rest of my bibliographic house in order before I’ll start tinkering with integration.