In addition to native Django ORM calls (to whatever DB you're using), we've also used tastypie to surface MongoDB and SOLR search results to REST endpoints.

Edit: I should mention that both were pretty painstaking the first go-around, but mostly due to my ignorance of the platform. I am thankful to know some more seasoned Tastypie users, so getting answers was pretty easy, and the Google Group is really good for Tastypie as well.