Hannu - 11:49 am on Nov 12, 2002 (gmt 0)

Are you saying 19% were bookmark visits and people spelling/compying the url in the browser address window?

and users clicking on links in e-mails, proxy server filtering of referrals and browsers set to not sending referrals.

...Are you saying Webtrends sees my own site as a referrer? But then the unique visitors do not add up with the number of visits.

Yes it does. And referrals are counted on a per-request basis so actually you can't use the numbers to derive uniques etc.