For travel health advice on the net,

Centres of disease control and prevention www.cdc.gov

Health recommendations for every country www.mdtravelhealth.com

International travel and health - e book by WHO www.who.int/ith/

Other sites : www.travellingwell.com.au

Government Sites :

Australia : www.dfat.gov.au/travel/
Canada : www.travelhealth.gc.ca
US : www.cdc.gov/travel/