Ghosts of India by Mark Morris
Synopsis: The Doctor and Donna go to India in 1947 and meet Ghandi.
Shining Darkness by Mark Michalowski
Synopsis: Two and a half million light years from earth the Doctor and Donna must defeat The Cult of the Shining Darkness.
The Doctor Trap by Simon Messingham
Synopsis: A ruthless hunter posing as a nineteenth-century nobleman decided the Last of the Time Lords would make the perfect prey.
Beautiful Chaos by Gary Russell
Synopsis: Not yet released
Also coming out in October is a collection of comics featuring the Tenth Doctor and Rose. Squee!
The Betrothal of Sontar
Fascinatingly enough, a new Martha book will be coming out on January 9th, 2009. The plot sounds like something you'd find in high quality fanfiction, which could be a very good thing.
The Story of Martha by Dan Abnett
Synopsis: Follow Martha Jones as she travels the earth preaching about the Doctor during the entire "year that never was."
Also, Four Tenth Doctor books will soon be published that feature no companion whatsoever. It is not clear however if these books take place between "Voyage of the Damned" and "Partners and Crime," or after "Journey's End." The first book comes out on January 9th, while the last three don't get released until April 16th. The idea of him all by himself kind of depresses me, but I may get the first book just to see how it turns out.
The Eyeless by Lance Parkin
Synopsis: The Doctor must battle alone to destroy a weapon of mass destruction while dealing with the ghosts of those it killed.
The Slitheen Excursion by Simon Guerrier
Synopsis: The Slitheen have a new tourist business where they send Aliens to ancient Greece to pretend to be Gods.
Prisoner of the Daleks by Trevor Baxendale
Synopsis: The Doctor is stranded on a space ship with some bounty hunters and their live Dalek prisoner.
Judgement Of The Judoon by Colin Brake
Synopsis: The Doctor must work together with the intergalactic police, the Judoon, to stop the Invisible assassin from terrorizing the sprawling spaceport, New Memphis.