John/Nick The debate on IP Addresses is a valid one. My own personal view is that using IPs as a unique identifier is acceptable in some situations, but totally wrong in others: An example is where ecommerce forms were using IP address to create a form id, and if the id is not the same from a POST, an error is displayed. A user behind one of those proxy pools (remember : AOL, other ISPs, and entire countries are behind those) could not proceed with a cart checkout because of that. However, in statistics, all we are saying is how many unique IPs we get hits from. It would not matter much if one users is seen as three IP addresses, since that is the nature of IP addresses. Crawlers do come from several IP addresses for the same search engine. Using sessions would be a great idea, except that some visitors do not have cookies (e.g. crawlers), so this is not a fool proof way of doing it. Presently, there is no bullet proof way of identifying a visitor that would work for all visitors (humans, bots, ...etc.), and we have to live with that limitation.