The 2008-2010 Specials should be watched between Series 4 & 5. There are also several minisodes. Here's the main watching order:

• Series 1

• Born Again (minisode)
• The Christmas Invasion (Christmas 2005)
• Series 2

• The Runaway Bride (Christmas 2006)
• Series 3

• Time Crash (minisode)
• Voyage of the Damned (Christmas 2007)
• Series 4

• Music of the Spheres (minisode)
• The Next Doctor (Christmas 2008)
• Planet of the Dead (Easter 2009)
• The Waters of Mars (Autumn 2009)
• The End of Time (Part 1) (Christmas 2009)
• The End of Time (Part 2) (New Years 2010)

• Series 5
  • Meanwhile in the TARDIS (Part 1) (minisode) - before The Beast Below
  • Meanwhile in the TARDIS (Part 2) (minisode) - before The Vampires of Venice
  • Good as Gold (minisode) - before The Lodger

• A Christmas Carol (Christmas 2010)
• Space / Time (minisodes)
• Bad Night / Good Night (minisodes)
• Series 6
  • First Night / Last Night (minisodes) - before The God Complex
  • Death is the Only Answer (minisode) - before Closing Time
  • Up All Night (minisode) - before Closing Time

• The Inforarium (minisode)
• The Doctor, the Widow and the Wardrobe (Christmas 2011)
• Pond Life (minisode)
• Series 7A: up to and including The Angels Take Manhattan
• P.S. (minisode)

• The Battle of Demons Run: Two Days Later (minisode)
• The Great Detective (minisode)
• Vastra Investigates (minisode)
• The Snowmen (Christmas 2012)
• Series 7B

• Doctor Who (1996 TV Movie)
• The Night of the Doctor (50th Anniversary minisode)
• The Last Day (50th Anniersary minisode)
• The Day of the Doctor (50th Anniversary Special)
• An Adventure in Space and Time (50th Anniversary Docudrama)
• The Five(ish) Doctors Reboot (50th Anniversary Spoof/Comedy)
• The Time of the Doctor (Christmas 2013)

• Series 8

• Last Christmas (Christmas 2014)
• Series 9
• The Husbands of ... (Christmas 2015)