The White House Historical Association has released an new online educational site allowing people to visit the White House on January 1, 1863 -- the day the Emancipation Proclamation was signed. Geared for middle school age students, "President Lincoln's White House: An Emancipation Day Visit" allows you to pick one of five roles -- messenger, widow, congressman, diplomat, spy -- and move around a few public rooms at the White House where historical people speak to your character.
I spent a few minutes poking around, and it seems like a good educational tool. It's a bit low-tech (after all, it is a free online program), but it should serve its purpose. The one challenge is that there doesn't seem to be anything for the characters to do except walk around and click on things to receive information -- so I'm not sure how long it will hold a student's attention.
You can visit yourself (or escort a school age visitor), by following this link.