How to balance SEO attractiveness versus counting clicks

Directory site

[anallawalla]

The business needs to count clicks to the advertiser's home page from their directory listing - to show ROI. This prevents offering a clean link. Any way to do both?

[buckworks]

<a href="http://www.example.com/" onClick="window.open('http://example.com/tracking-stuff/'); return false;">Example.com</a>

[anallawalla]

Thanks, Buckworks!

[ColinG]

Except opening a new window does not send a referrer to the target site. The alternatives are to use a on click redirect script such as the one google uses or to use a javascript rewrite of the script to include the redirect.