List of vaccination resources that I find particularly reliable:

CDC's National Immunization Program	Allied Vaccine Group
Canadian Pediatric Society	Children's Hospital of Philadelphia (CHOP)
Children's Vaccine Program at PATH	Canadian Immunization Awareness Program
Immunization Action Coalition (IAC)	National Network for Immunization Information
Vaccine Page	Mike Gunderloy's Vaccination Page
Issues in Immunization	MMR - The Facts
National Partnership for Immunization	iVillage's General Vaccination Issues
MDs4Kids Vaccine Information Page	Vaccine Information for the Public & Health Professionals

Other useful resources:

Pink Book Epidemiology and Prevention of Vaccine-Preventable Diseases

Australian Immunisation Handbook

PubMed National Library of Medicine's online access to Medline scientific articles

Publications (Books) for Health Care Providers and Parents

Immunization Schedules - Country by country

Canadian Pediatric Society's "Your Child's Best Shot: A Parent's Guide to Vaccination" by Dr. Ronald Gold, MD, MPH

Informative articles:

"Mistaking the Enemy"

Comparing vaccine risks with disease risks (Consumer Reports article)

Hot Shots - "Some would have you believe vaccines do more harm than good. Here's why that's wrong"

The Promise of Vaccines: The Science and the Controversy

Why Immunize?

Vaccines: An Issue of Trust from Consumer Reports magazine

Concerns about Immunization (British Medical Journal)

Summary of Notifiable Diseases, United States - 2001 (CDC)

Shot ... or not? What to make of the anti-vaccination information

Shot ... or not? Misconceptions about immunizations

Shot ... or not? Glossary of individuals and groups encountered