Anonymize all your external links with the mastrcoder anonymizing service.
You can use this plugin to prevent your site from appearing in the server logs of referred pages as a referrer. The operators of the referred pages cannot see where their visitors originate from.
For example, this plugin will automatically convert all external links to this format http://anonymizer.mastrcoder.com/index.php?q=http://k0nsl.org/
This produces an anonymous link to k0nsl.org which prevents the original site from appearing as a referrer in the log files of the referred page. This will apply to all external links - except for the ones you decide to exclude.