The Horace Mann site had a wide selection of articles. Be forewarned, I haven't read anything yet.
Motivating Students by Barbara Gross Davis looks promising.
What Do Students Want (and what really motivates them)? also looks good.
Hiding the Aspirin in the Applesauce might imply tricking students into learning. None of us would ever do that, right?
If you have any ideas or contributions, feel free to post a comment or email me. Thanks!