Explorers 

Discoverers Web (http://www.win.tue.nl/cs/fm/engels/discovery/alpha.html) (6th and up)
An alphabetical listing makes this a great place to begin your search about explorers, with links to other biographic sites.  

Explorers (http://edtech.kennesaw.edu/web/explorer.html)(6th and up)
Another big alphabetical listing of sites about explorers, conquistadors and the Age of Exploration.

Explorers of the Land (http://www.bham.wednet.edu/bio/land.htm) (5th and up)
Magellan, Cortez, Pizarro, First Peoples, and more.  Find links about these famous explorers and cultures.

Explorers of the World (http://www.bham.wednet.edu/bio/explore.htm) (5th and up)
Those who dare to challenge the boundaries of space, time, ignorance and science are the type of people found at this site.  Accurate, detailed information, with some links to other sites.  Make sure you check here for your person.