The future of medicine is in standardizing medical decision pathways for both diagnosis and therapeutics. Some resources that are valuable for helping find evidence-based medical guidelines include the National Guideline Clearinghouse from US Department of Health and Human Resources and OpenClinical.
The American College of Physicians also has a great list of Clinical Practice Guidelines. Tobacco cessation guidelines can be find here.
AHRQ has a fabulous list of Clinical Preventive Services guidelines, which includes recommendations for all sorts of screening exams, including diabetes, cancer (lung, breast, ovarian, prostate...), depression, and AAA.