You can use the Feedback Tab, which is present on all of the site's main pages. It should appear as a "clothes tag" on the left-hand edge of your browser window. WOWIO! employees monitor and respond to activity there.
People also tend to post their suggestions in the forum's Help section: http://www.drunkduck.com/forum/9896/. This can be useful to gauge interest in a suggestion and work out potential kinks in any ideas.
Keep in mind that the admin and moderator staff do not do any coding for the site, so even if they think something is a great idea, all they can do is suggest to the programmers that it be implemented. The programmers have a lot of priorities when it comes to the site, and better know the limitations and possibilities of the codebase, so it may be easy to implement some things immediately and others may never get realized.