while not technically a "street party", Kali's Full Moon parties on Friar's Bay beach used to be like that...they used to occur on the night of the actual full moon, but now they supposedly occur on the saturday night closest to the full moon...you may want to look into the particulars of that

and if you happen to be in the area, Nassau Bahamas, Barbados, Tobago have pretty cool weekly street parties/jump ups <img src="http://www.traveltalkonline.com/forums/images/graemlins/toast.gif" alt="" />