Neither Here Nor There by Bill Bryson - because it is still the funniest book I have ever read, and the only one that still makes me snort with laughter on re-reading it.
The complete Hitchhikers Guide to the Galaxy - because it is just bloody marvellous.
The Crow Road by Ian Banks because it is clever and funny and sad and I loved Prentice when I was a teenager.
All Quiet on the Western Front - war is bleak and shit and pointless on either side.
Black Beauty - because Ginger , just because Ginger :(
(I accept that these may not be everyone's cup of tea, but they would be my Desert Island books)