BBC and Penguin are releasing a short story each month devoted to each Doctor. The first was written by Eoin Colfer. Wasn't too bad but I didn't think he captured the grouchiness.
Keep scrolling through the list, you'll also find new adventures and a bunch of re-issues of the Target novelizations of the early episodes.
http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Ddigital-text&field-keywords=doctor+who
http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Ddigital-text&field-keywords=doctor+who