...Bibliometrics are probably the most useful of a number of variables that could feasibly be used to measure research performance....
There are data limitations where researchers' outputs are not comprehensively catalogued in bibliometrics databases.
The obvious solution for this is Open Access: All UK researchers should deposit all their research output in their Institutional Repositories (IRs). Where it is not possible to set access to a deposit as OA, access can be set as Closed Access, but the bibliographic metadata will be there. (The IRs will not only provide access to the texts and the metadata, but they will generate further metrics, such as download counts, chronometrics, etc.) ...
The open access movement:
Putting peer-reviewed scientific and scholarly literature
on the internet. Making it available free of charge and
free of most copyright and licensing restrictions.
Removing the barriers to serious research.
I recommend the OA tracking project (OATP) as the best way to stay on top of new OA developments. You can read the OATP feed on a blog-like web page or subscribe to it by RSS, email, or Twitter. You can also help build the feed by tagging new developments you encounter.