Wiki pages really have no seo value anymore, if you can find a spot where nobody (editors ) are looking it will stick for a while and you'll get a trickle of traffic. If it hangs around long enough it will get scraped and you'll also get a link in answers.com and some of the other wiki scraper sites.
like someone already mentioned, find a niche page and stick your link in the middle of the other "external links" sections. If you do have a quality site with really good content and want to add it to a main subject, it helps if you have no ads on it. At least this has been my experience, spamming wiki.