My bestseller for this age -- indeed, for any age -- is The Wolf's Footprint, which has a section to itself. You can find out more about it by following this link.
But I've written quite a few more books for this age-group.
A Feasting of Trolls tells of how Ivar tries to rescue his family from persecution by greedy trolls -- helped by the farm's cat, who has a secret...
Master Thomas Katt features another cat -- but this one seems to have turned into a sea-captain!
'And his own tomb, when he died, had a carving of him lying asleep with his hand resting on a sleeping cat. Written on his tomb are the words: Here lies the Tom-Kitten that grew to be a Tom-Katt.'
Odin's Monster is set in the Viking Age. It tells the story of Thord Cat, a poet who refuses to sing the praises of a man known to be 'an oath-breaker, a killer and a witch.'
In revenge the witch creates a monster and sends it against Thord Cat. He must do the witch's bidding or die...
Knocking Jack is a tale of a noisy ghost, or poltergeist.
Michaela's Mum has always wanted to live in a really old house and gets her chance when old Mr. Wheeler asks her to house-sit for him.
But Mr. Wheeler's old house already has a resident -- Knocking Jack, the ancient ghost who has lived there longer than anyone else.
Other books that 8-10 year olds (and even those a little older) may enjoy are The Saga of Aslak Slave-Born and The Bone Dog.