Books set in the future
The thing about fantasy is that it has to be set somewhere. If you don't want to set it in the present world, then the future is as good a place as any to hide it. And because it is fantasy, everyone's view of the future is totally different. These books do tend to be a bit grim, though. See my article 'Utopia'.
Books for younger readers
The City of Ember is built to last, but the once bulging store rooms are empty now. What will the people do to help themselves?
'We, Cosmo Hill, are the world's only Supernaturalists.'
Cosmo grinned weakly. 'What? You don't like clothes?'
'That's naturists, Cosmo. And nobody does that any more, not with the ozone layer spread thinner than cling film. We call ourselves Supernaturalists because we hunt supernatural creatures.'