Definitely music biographies. I've just finished reading:
Deborah Curtis' Touching From A Distance.I strongly recommend this one. It's very intriguing and it's one of those that you don't stop reading until you read the last word. There's also a curious photo of Ian, the last picture taken before he departed. You can clearly see the madness in his pale blue eyes.
Now onto
David Nolan's Bernard Sumner Confusion. This one's not official but still interesting. Some curious photos too of Barney playing the melodica and Martin Hannett, like a mad scientist, showing Barney a few things on the ARP Omni.
They've become really trendy in 2007!
Chris