General Civil War Interest:
http://www.twitter.com/civilwarwp
This is a fun Twitter feed about what took place on any given day in the war era.
This site is operated by the Civil War Trust, and has tons of good information, including the sesquicentennial and efforts to preserve Civil War battlefields across the nation.
As evidenced by the title, a fairly comprehensive site dealing with the war.
http://www.civilwartraveler.com
Informative site devoted to Civil War tourism, for those interested in traveling to war-related locales.
http://www.historynet.com/sesquicentennial-partnerships
Information on sesquicentennial commemorations around the country, and links to various states and locales…the historynet.com site in general is a treasure for history lovers.
Related to Cold Glory:
http://www.nps.gov/apco/index.htm
National Park Service site for Appomattox Court House National Historical Park.
Falls of the Ohio State Park
http://www.wnpa.org/freepubs/PAAL/Battle_Palmito_Ranch.pdf
Excellent information on the Battle of Palmito Ranch, including maps and a photo of the last man to fall.
http://www.okhistory.org/outreach/military/fortwashita.html
Fort Washita
Oklahoma Historical Society
The site for the sesquicentennial commission in my home state.