CIA The World Fact Book - Country by country listing of demographics, economic, and cultural facts that can prove helpful to researcher.
XE - A reliable and up to date mid market currency conversion site. Historic information under Tools is very enlightening.
U.S. Department of State Travel Alerts - In my opinion it is written with a conservative take, however Alerts are none the less something all global travelers should be aware of.
Sites Atlas - A detailed collection of political and physical maps of every country in the world.
World Time Zone - An essential tool to manage communications.