Other fictional worlds can inspire spoofs (see Bored of the Rings). The big problem I think with creating worlds is you can get so "into" what you have dreamt up, it's easy to forget the story you're meant to be writing. The world can take over but shouldn't in my view (though it can be a kind of a character as it is in Tolkein and Lewis's Narnia series).
A good fictional world is one you can visualise, one you perhaps want to spend time in but which doesn't drown out the story. It is one where the story itself couldn't possibly happen anywhere else.