A partial list of television shows that Obama has appeared in

I edited out the documentaries and things that the president has to appear in, courtesy of IMDB.
Having said that, our celebredent has been busy.  Not in the White House, of course...

2012 CMT Music Awards (TV movie)
2012 Late Night with Jimmy Fallon (TV series)
2012 Ali 70 from Las Vegas (TV movie)
2012 Betty White's 90th Birthday: A Tribute to America's Golden Girl
2007-2012 Today Show
Himself
– Episode dated 13 January 2012 (2012) … Himself (as President Barack Obama)
– Episode dated 2 February 2009 (2009) … Himself
– Episode dated 23 September 2008 (2008) … Himself (as Sen. Barack Obama)
– Episode dated 3 January 2008 (2008) … Himself
– Episode dated 28 December 2007 (2007) … Himself

2011 WWE Tribute to the Troops (TV movie)
2006-2011 The Tonight Show with Jay Leno (TV series)
Himself
– President Barack Obama/Yo-Yo Ma & Friends (2011) … Himself (also archive footage) (as President Barack Obama)
– Episode #17.50 (2009) … Himself (as President Barack Obama)
– Episode #15.185 (2007) … Himself
– Episode #14.219 (2006) … Himself

2007-2011 The Situation Room (TV series)
Himself
– Episode dated 20 August 2011 (2011) … Himself
– Episode dated 1 December 2008 (2008) … Himself
– Episode dated 5 July 2007 (2007) … Himself

2011 Race to the Top Commencement Challenge Special (TV movie)
2011 Get Schooled: Race to the Top (TV movie)
2011 Jeopardy! (TV series)
Himself - Video Greeting

2005-2011 The Oprah Winfrey Show (TV series)
Himself
– All New! President Obama and First Lady Michelle Obama (2011) … Himself (as President Barack Obama)
– Episode dated 18 October 2006 (2006) … Himself
– Episode dated 19 January 2005 (2005) … Himself

2011 All Together Now: A Celebration of Service (TV special)

2011 The 83rd Annual Academy Awards (TV special)

2010 WWE Tribute to the Troops (TV movie)

2010 Christmas in Washington (TV movie)

2010 MythBusters (TV series documentary)
Himself
– President's Challenge (2010) … Himself

2005-2010 The Daily Show with Jon Stewart (TV series)
Himself
– Barack Obama (2010) … Himself
– Barack Obama (2008) … Himself (as Sen. Barack Obama)
– Barack Obama (2008) … Himself (as Senator Barack Obama)
– Barack Obama (2007) … Himself (as Sen. Barack Obama)
– Barack Obama (2005) … Himself (as Sen. Barack Obama)

2010 A Conversation with President Obama (TV movie)
2010 Stand Up to Cancer (TV special)

2007-2010 The View (TV series)
Himself
– Episode dated 29 July 2010 (2010) … Himself
– Episode dated 27 September 2007 (2007) … Himself (as Senator Barack Obama)

2010 The Apprentice (TV series)

2010 The Real World (TV series)
Himself
– From D.C., with Love (2010) … Himself
– White House, Glass House (2010) … Himself


2009-2010 The Tonight Show with Conan O'Brien (TV series)
Himself
– Episode #1.138 (2010) … Himself
– Episode #1.2 (2009) … Himself

2009 Christmas at the White House: An Oprah Primetime Special (TV special)

2008-2009 Access Hollywood (TV series)
Himself
– Episode dated 25 September 2009 (2009) … Himself
– Episode dated 11 July 2008 (2008) … Himself
– Episode dated 10 July 2008 (2008) … Himself
– Episode dated 9 July 2008 (2008) … Himself
– Episode dated 8 July 2008 (2008) … Himself

2009 Get Schooled: You Have the Right (TV documentary)
Himself

2009 2009 MLB All-Star Game (TV movie)

2008-2009 The Colbert Report (TV series)
Himself / Himself - Guest
– Episode #5.76 (2009) … Himself - Guest (as President Barack Obama)
– Hillary Clinton/John Edwards/Barack Obama (2008) … Himself (as Senator Barack Obama)

2009 Inside the Obama White House (TV movie)

2009 Sky News: Live at Five (TV series)

2009 A-studio (TV series)
Himself
– Episode dated 1 April 2009 (2009) … Himself

2009 President Barack Obama: The Man and His Journey (video documentary)
Himself

2009 We Are One: The Obama Inaugural Celebration at the Lincoln Memorial (TV movie)

2009 Be the Change Inaugural Ball (TV movie)

2006-2008 Meet the Press (TV series)
Himself
– Episode dated 7 December 2008 (2008) … Himself
– Episode dated 27 July 2008 (2008) … Himself (as Sen Barack Obama)
– Episode dated 22 October 2006 (2006) … Himself (as Sen. Barack Obama)
– Episode dated 22 January 2006 (2006) … Himself (as Sen. Barack Obama)

2008 The Barbara Walters Summer Special (TV series)
Himself
– Barbara Walters Presents: The 10 Most Fascinating People of 2008 (2008) … Himself
– Barack and Michelle Obama (2008) … Himself

2008 Late Edition with Wolf Blitzer (TV series)