Things to do by country.

The Foreign and Commonwealth Office of the British government has a handy "don't go there" list of countries. The FCO even has a handy set of links to other government's sites.

The US Department of State has similar listings, though not nearly as obvious.

< a href="http://www.safewateronline.com/">Safe Water for International Travelers provides a simple rating of countries' water quality, so you can know if it's safe to drink the tap water or if you need to treat the water or buy bottled water to avoid diseases.