Mohsen Sadatsafavi, from UBC, has created a great
firefox extension for extending searches in Pubmed with connotea. It’s called PubConn.
There is a good bit of information on that page, and from there a short description of it’s features include:

- You are doing a search in Pubmed and find an article familiar to you. Have you bookmarked this paper before? Currently, the best option is to have a Connotea page open and search for the Pubmed record in your bookmarks (e.g. by using paper’s PMID), or press the ‘add to Connotea’ button to see if you have already bookmarked that paper. Using Pubconn, your bookmarked records in Pubmed are highlighted and the tags and descriptions you have provided for the bookmarked are displayed next to the Pubmed record.

- You are doing a literature review in a collaborative project with several other people, you have created a user group in Connotea and are bookmarking relevant papers in that group. When you start searching, you are interested in knowing whether a particular paper has already been reviewed by one of your teammates. Using Pubconn, all the bookmarks highlighted by your colleagues are highlighted.

- When you are doing a Pubmed search, you are interested to see if other people have bookmarked any of the papers you have in your search results. Currently, you should query Connotea for each and every record returned by Pubmed. Using Pubconn, any of the Pubmed records that have been bookmarked are highlighted within your search results.

It also works offline and online.

This is a Fire fox extension file and you can get the xpi file here.