I have long suggested that we have a single place to access standards, implementation guides, test scripts, guidelines, and code sets.
The National Library of Medicine is building a national resource for vocabularies and code sets.
In the meantime, the best centralized resource we have for HIT related knowledge assets is the United States Health Information Knowledgebase (USHIK)
USHIK is an on-line, publicly accessible registry and repository of healthcare-related data, metadata and standards.
In particular, I think you will find the Meaningful Use Stage 2 criteria listed on the site (including the quality measures) to be particularly useful.
Go to the USHIK site and click on Meaningful Use box at the top left. You will be directed to that site.
Once there you can click on Value Sets or click on Download (on left-hand side) to get to the files.
Thanks much to AHRQ and Michael Fitzmaurice for creating and curating USHIK.