Happy birthday.
Maya 6 killer tips is a great book and well worth it in anyones reference materials, anther great book is maya 6 (or 8 now) the complete reference, and if your so inclined to get every bit of use out of maya, Complete Maya programming - An externsive guide to MEL and the C++ API though it can be heavy going if your not programming savy with terms and the maths.
"No pressure, no diamonds" Thomas Carlyle