I contribute to a small web database for people doing genetics on ants. To encourage citations, I'd like to display links to articles recently citing our publication.
Like what would appear on google scholar if you click the "Cited By" link.
EDIT by lh3 for a recent update on CiteXplore: The following URL returns an HTML page showing the number of citations from Web Of Science. We can just do a regex matching to get the number out. Note that to compose the URL, we have to add "&citedCount=1"; otherwise it does not work. The UKpmc also gives the Web of Science citation numbers, but it uses AJAX, which is a little harder to parse.
Maybe a bit of topic, but still related. I have been struggling to capture scholar as well.
But you might find http://www.citedin.org interesting here. Through Citedin.org you can find which resource other then from the literature cite you pmid. (ie. Wikipedia, Uniprot, blogs, etc). There is an API to incorporate this in your website
You can use Europe PMC (former UKPMC) API to retrieve a list of publications which cite a given paper. For a RESTful request you can construct the URL using the PMID of the paper you want retrieve citations for: http://www.ebi.ac.uk/europepmc/webservices/rest/MED/[PMID]/citations. You can also view citations on the website itself, they are visually presented in a citation graph, and the list of papers citing a publication can be found under Citations tab.