I guess (and know) that you have, primarily, two options:
1. Email me.
2. Or, if you don't have the time or the patience to fire up that email client and then send me a comment, or if, on a more subtle level, you want to do it anonymously; you can use this form: Jus' fill it up and click on the Send button.
(Of course, there are innumerable alternatives. If you maintain a weblog, you can add a post, and then send me the link. If you maintain a pigeonry of homing pigeons, you can probably send me a pigeongram, but, that would be taking it too far, wouldn't it? Maybe you can just shout your message from your office window?)
Many thanks to thesitewizard.com for the PHP script framework which I used blatantly for tweaking my own feedback form.