Specific Topic Websites:

Doing History (several professions or jobs with photos)
http://hewit.unco.edu/dohist/themes.htm

Anasazi
http://teacher.scholastic.com/researchtools/researchstarters/native_am/index.htm
http://www.blm.gov/co/st/en/fo/ahc/who_were_the_anasazi.html

Spanish/Hispanic Settlers
http://pueblo.org/history
http://coloradovirtuallibrary.org/content/felipe-baca
http://coloradovirtuallibrary.org/content/casimiro-barela

Miners
http://www.miningbureau.com/
http://hewit.unco.edu/dohist/mining/themes.htm

Government
http://www.netstate.com/states/government/co_government.htm
http://www.colorado.gov/cs/Satellite/CO-Portal/CXP/1165693060260

Immigrants
https://wiki.familysearch.org/en/Colorado_Emigration_and_Immigration

Recreation and Sports
http://www.colorado.com/Recreation.aspx
http://www.denver.org/things-to-do/sports-recreation/

Explorers (Spanish, French, and American)
http://www.thingstodo.com/states/CO/history.htm

Trappers, Traders, and Mountain Men
http://hewit.unco.edu/DOHIST/trappers/themes.htm
http://www.legendsofamerica.com/we-explorerindex.html

Famous People of Colorado
http://www.historycolorado.org/kids-students/biographies-notable-coloradans
http://www.colorado.gov/dpa/doit/archives/arcbiog.html

Colorado Symbols
http://www.enchantedlearning.com/usa/states/colorado/
http://www.colorado.gov/dpa/doit/archives/history/symbemb.htm

General Websites

http://www.infoplease.com/ipa/A0108189.html
Lots of state information including famous residents and statistics

http://www.netstate.com/states/intro/co_intro.htm
Information about economy, people, and government