Sessions and URLs without ? or &

I am using sessions to track the user's movements around a website and as I can't rely on the user accepting cookies, I am passing this from page to page as part of the URL. On the basis of the recent mailings on simple, search engine-friendly URLs, I would like to use links from page to page in the form http://www.foo.bar/products/widget I presume that the session ID would have to be passed as another "directory-like" parameter at the end of the URL - ie in the form http://www.foo.bar/products/widget/234ji8h8h34j32h48sdf (or whatever), but this seems undesirable as the session ID will be included in the link from the search engine. It means, for instance, that every visitor coming from the search engine will have the session ID in their URL. It also negates the other main benefit of passing parameters in this way - that the url is short and logical (people typing in the URL will not know that they don't need the "234ji8h8h34j32h48sdf" section to go the the correct product page). What is the best solution to this problem? One way that I can see would be to find out whether the visiting browser is a web-crawling robot and leave off the session ID section of the URLs for all non-human visitors to the site. Would HTTP_USER_AGENT help with this, and if so, what would I have to look for in it? Alternatively, is there a way of passing the session ID from one page to another without using cookies and without it appearing in the URL? Any alternative suggestions would also be appreciated. Thanks Andy Clarke ----------------------------- Andy Clarke 78 West Kensington Court Edith Villas London W14 9AB Phone: 44 (0)20 7602 3382 Mobile: 07947 418177 Email: andy@kinonet.com -----------------------------