Fergie's recent single (aptly titled "Fergalicious") is a definite example of current crack music, along with the Pussycat Dolls' "Wait A Minute". Both of those songs make me want to get up and dance around the room all day.
My current crack song is
"Dangerous" by the Ying Yang Twins. It's an interesting mix of Wyclef Jean's vocalizations, samplings of both "Maneater" by Hall and Oates (the chorus part) and "Black Betty" by Ram Jam (the latter occurring in the last couple of seconds of the song), and a wicked bass loop to match.
Plus the YouTube video I linked above for the song? Definitely fits the mood of the song.