I have just read on Steve Schofield Weblog that the IIS team have just released a dynamic IP restrictions module. This module amoung other things will allow you to temporerilly block any client that makes too many requests. I would imagine this would be invaluable for anyone out there who runs any busy websites. I inperticular used to be part of a team which ran the website for an Arena and whenever a popular act was visiting and tickets were about to go on sale people would sit on the site using the refresh button constantly sometimes causing the site to go down. This module could have been used to discorouge and indeed stop this behaviour.