The most famous and well regarded certifiction is from IBM. i.e IMB 486(OOAD & UML certification). I am also in a proces of preperation for the same. Good literature can be found at
www.objectsdesign.com, CFW and bala questions are excellent. Books by Martin Fowler(UML Distilled) and Larmen(Applying UML and
patterns) are good as also prescibed by IBM.