In the novel 'The River Sea' by Eva Ibbotson, Maia is the main character. She goes to live with her aunt, uncle and cousins Beatrice and Gwendolyn in the Amazon jungle, which, of course, is in Brazil. It's a beautifully written novel, and it has made me really like this name. It, in my opinion, is much prettier than 'Maya'. :)
The Greek goddess Maia appears as a character in the "Mary Poppins" books by P.L. Travers. She and her sisters are stars (the Pleiades), come down to earth to celebrate Christmas in a department store.