But an online business that becomes the victim of an assault or electronic demonstration would argue that disruptive activities are destructive to its income. Maybe that's the whole point. This is a pure performance issue that you have hopefully already considered. Restrict the number of Web searches that can be successfully initiated from a specific browser or IP client in a given time period. Restrict repetitive same-criteria searches.
Legitimate surfers conduct multiple searches on different criteria most of the time.
Establish a means to locally sever a connection made by a Floodnet user. Consider using products with strike-back capabilities. For example, in response to attacks, Secure Computing's Sidewinder firewall launches a daemon that will trigger the offensive techniques of your choice. Strike-back products from other vendors are in the works. Make sure you have no subject line and remove your signature.