Going somewhere over the holidays? This collection of Web sites should help travelers stay informed and healthy while traveling abroad. The first Web site is the home page the Aviation Health Institute, a nonprofit organization devoted to researching health effects of traveling by plane (1). The Web site focuses on deep vein thrombosis, offering news items, research summaries, prevention tips, and more. For those planning ski trips or other mountain activities, the next two Web sites are worth a visit. The first is a comprehensive source for information on altitude sickness from the International Society for Mountain Medicine (2), and the next offers detailed information on hypothermia, frostbite, and other cold weather injuries (3). Both sites provide prevention and treatment information. Those headed for warmer regions should find the Web site on heat-related illnesses from the University of Maryland a useful resource (4). Of course, travelers must worry about more than exposure to elements. The next four Web sites provide detailed information on diseases and parasites -- tropical ones in particular. The health and medical advice provided by ComeUnity is intended for those traveling to Asia for adoption purposes, but the clearly presented information in this Web site should prove useful for any traveler (5). A little dengue fever with your feijoada? Travelers to Brazil and other South American countries may want to check out this Web site from the Centers for Disease Control (6), which offers information on dengue (increased dengue activity noted in Brazil), malaria, and Chagas disease, as well as vaccination information and tips on how to stay healthy. The following Web site (7), also from the CDC, is a comprehensive resource for information on intestinal problems due to contaminated food and water -- a common problem when traveling. The last Web site contains an entertaining if somewhat disturbing article from the Straight Dope about the tiny blood-sucking tropical catfish that will sometimes mistake the human urethra for the gill cavities of a large fish -- its usual dining venue (8).