Blocking sites

I am trying to locate a company that will provide us with a list of undesirable
WWW sites that I can feed into our proxy server to deny access to these sites.

I remeber a while back somebody advertising a similar service which was aimed
at educational sites where they would send a list on a weekly basis.

Any information would be appreciated.

Jason Crow               Salomon Brothers International Limited
<jason.crow@sbil.co.uk>  -----------------------------------------------
Information Security Manager                    Tel: +44 (0)171-721-2580
Business Technology Organisation                Fax: +44 (0)171-721-2605