Ooh, you enjoy Pullman? I was just about to recomend him; definitely my favourite author ever. His Dark Materials is brilliant, the Sally Lockhart series is excellent too and last year I read The Broken Bridge which was also very very good. Oh, and Clockwork is the best short story written ever.
Other recomendations, let's see...
Haven't read
Robin Jarvis for a long time, but I remember him being very good. Did the Depford Mice and Wyrd Museum series of books. The thing I loved most about these books was how
dark they were, so they might appeal to a Dahl fan. Pretty soon all the characters end up diying in them, which is fun when they're talking birds and vermin. It's been a while but I'll give Jarivs 4/5.
And if you like Harry Potter then you might also consider Diana Wynne Jones's
Chrestomanci series. Actually, those books are really good and I'd almost forgotten about them. Funny, well-written and well-plotted. Plus it has parralel universes, which are always nice. Again, it's been a while but I think I loved these books... I should read them again. 4.5/5
And I mentioned this briefly before, but I really liked reading
The Princess Bride - a witty fairytale satire that's ingeniously written. If you're familiar with the film then the book is at least ten times as good and will appeal to anyone who likes a good adventure story. 5/5
In the mean-time I need to polish up on Dahl. ;