THE PILOT WAS ATTEMPTING TO LAND ON RUNWAY 18 AFTER HE HAD BEEN INFORMED OF WINDS FROM 260 DEGREES AT 19 KTS, GUSTING TO 30 KTS. JUST AS HE WAS ABOUT TO TOUCH DOWN, A GUST OF WIND CAUGHT THE ACFT, DRIVING THE LEFT WING TO THE RWY. THE NOSE GEAR COLLAPSED AND THE ACFT SLID TO A STOP. THE OWNERS HANDBOOK, IN THE SECTION ON CROSSWINDS, PROVIDES NO GUIDANCE ON A CROSSWIND LIMIT. EVEN WITHOUT GUSTS, THE CROSSWIND COMPONENT COMPUTES TO NEARLY 19 KNOTS.