Well, the most popular few would be Space Oddity, Ashes to Ashes, Life on Mars? and "Heroes". Ashes to Ashes is especially popular and one of the first Bowie songs I ever listened to. Oh, and then there's Loving the Alien, Fantastic Voyage, The Next Day and the two newest songs from him, Sue (Or in a Season of Crime) and 'Tis a Pity She Was a Whore. Listen to any of them and tell me what you think. Oh, and "Heroes" is the one Blondie covered.