Opening Theme:
#1: "the WORLD" by Nightmare (eps 1-19)
#2: "What's Up People?!" by Maximum the Hormone (eps 20-37)
Ending Theme:
#1: "Alumina" by Nightmare (eps 1-19)
#2: "Zetsubou Billy" by Maximum the Hormone (eps 20-36)
#3: "Coda ~ Death Note" by Yoshihisa Hirano (ep 37)
(Вообще такие вопросы легко выясняются на http://www.animenewsnetwork.com/ , например)