I’ve published my CopyPMID Chrome extension in the Chrome web store. It’s one of the most boring extensions in the world, as all it does is add a button to PubMed pages to allow quick copying of the PubMed ID to the clipboard, but I needed to publish it on the web store so I could use it myself! I use it quickly import PubMed references into JabRef by PMID. The source code is also available on my GitHub page.