Infectious disease surveillance systems have embraced the Internet. ProMED-mail is a rapid reporting system of emerging infectious diseases in humans, animals, and plants. ProMED-mail relies on local news sources like newspapers and their web sites and local rapporteurs submitting reports of unusual events such as the first English language report of SARS. Each report on ProMED-mail is placed into perspective by an expert in the field and whether the report is credible or not is discussed. Provider-based surveillance of travelers has also become increasingly sophisticated. Monitoring disease trends geolocation of acquired diseases among travelers can inform both pretravel advice and posttravel management. Data from sentinel travelers upon their return to medically sophisticated environments can also benefit local populations in resource-limited countries. Networks such as GeoSentinel have provided cumulative trends in travelrelated illness to assess pretravel risk for mass gathering events such as the Beijing Olympic Games or the FIFA World Cup in South Africa. Data provided by the GeoSentinel also helped in determining the seasonality of dengue by region of travel and risk of acquiring schistosomiasis by destination. Global surveillance of travel-related disease represents a powerful tool for the detection of infectious diseases. Such data should encourage clinicians to take a detailed travel history during every patient encounter. © 2011 John Wiley & Sons, Ltd.