The American Civil War Home Page has extensive categorized links, many of which I couldn't find anywhere else.  

  The United States Civil War Center has great links, but the content is advanced.  

  The Civil War - Live is a great site (even thought they took the background graphic I made), with lots of biographies (click on the reference button).

  The Library in the Sky's Civil War links page has tons of links.  

  Dakota State University's Civil War Page has the most thorough set of links - plus, they're nicely categorized.  

  The Library of Congress' Selected Civil War Photographs has other good source material as well.

  A good Civil War timeline from the Library of Congress.  

  The History Place has another Civil War timeline to will help you get a feel for the events of the war.  

  Some links to African American Troops in the Civil War.  

  The 54th Mass. Volunteer Infantry, Co. 1 portrays the experience of the African American soldier in the American Civil War in South Carolina. There are extensive links to other information on African Americans in the Civil War around the nation.  

  Duke University's Civil War Women.  

  The Civil War Maps Exhibit has just that and more! Looking for a timeline? You've come to the right place. Although commercialized, this site has other Civil War links and photos.  

  The Valley of the Shadow profiles and interweaves the histories of two communities on either side of the Mason Dixon Line during the Civil War.  

  The diary kept by schoolgirl Alice Williamson at Gallatin, Tennessee from February to September 1864. The main topic of the diary is the occupation of Gallatin and the surrounding region by Union forces under General Eleazer A. Paine. The diary relates many atrocities attributed to Paine. Frequently mentioned is presence of black contrabands in and around Gallatin, attempts to give them formal schooling, and their abuse by Union Eastern Tennessee troop.  

  When all else fails, you can always search The Library of Congress.