Some sites you may not have come across elsewhere.....

Bandolier Uk - An independent journal about evidence-based healthcare
Clinical Knowledge Base UK NHS - Clinical health outcomes knowledge base
The Clinical Governance Research and Development Unit R&D within clinical governance. Example audits and how to create audit protocols.
The SDO Programme Uk - Producing research evidence directed at improving the organisation and delivery of health services
Cebmh Centre for evidence based mental health.
NPCRDC The National Primary Care Research and Development Centre - Manchester.
Oncolink U.S. site - a major resource for oncology related searching
National Guideline Clearinghouse U.S. - Department of Health, a public resource for evidence-based clinical practice guidelines