Combining the possible effects of this storm with the flooding that just occurred in Europe, the insurance and re-insurance businesses may be seeing largish draws on their reserves.
Speaking of floods, it is worth noting that people in the Ohio Valley and Appalachia should be keeping a sharp eye out on where Katrina is gonna go, because it definitely has the potential to cause some massive flooding. Camille killed about as many people in Appalachia as it did on the Gulf Coast. Of course, that's leaving New Orleans out of it. If the worse case scenarios play out there, nothing will rival that (except a 9.0 earthquake in Cali).