I don't know how talented you are but here's a very hard one:
Garlic Jr's Palace from Movie1: Dead Zone
It's large and complex, but if you make it you'll prove yourself. If you want an easier one then i'd like to see the inside of the Big Gete star from Movie 6 where Goku and Vegeta fight Cyborg Cooler (not Meta Cooler)
Or how about the icy area in Movie 7? That's pretty easy if you know clipping and vertex manipulation. As you can tell, I like the movies.
Maybe someone should sticky this and use it as the Final Mapping Requests Thread like the modelling one but for maps, and mappers can come get ideas and inspiration, and the community can show what they want to see