From a PubMed Central E-Mail List and Website:
PubMed Central (PMC) PMC is happy to announce the addition of a citation exporter feature. This feature makes it easy to retrieve either styled citations that you can copy/paste into your manuscripts, or to download them into a format compatible with your bibliographic reference manager software.
When viewing an Entrez search results page, each result summary will now include a “Citation” link. When, clicked, this will open a pop-up window that you can use to easily copy/paste citations formatted in one of three popular styles: AMA (American Medical Association), MLA (Modern Library Association, or APA (American Psychological Association). In addition, the box has links at the bottom that can be used to download the citation information in one of three machine-readable formats, which most bibliographic reference management software can import.
The same citation box can also be invoked from an individual article, either in classic view (with the “Citation” link among the list of formats) or the PubReader view, by clicking on the citation information just below the article title in the banner.