Have you thought about doing paid subscriptions that would remove ads for those who are subscribers? I would have no problem paying $3-$5 a month or so to help finance this site with or without ads. Also, I order on Amazon a lot but always forget to go through the link on the Support WKC page. If you could add a link to amazon that is under the banner and therefore on any page of the website I think it would generate a lot more revenue for you.
Another thought is adding a few stickers or something like that to anyone who donates directly through the paypal donate link and having a post somewhere acknowledging those who have donated that way. If sending out stickers every time someone donates can be a bit hard to keep up with, you could ship them at the end of the month instead of on demand as well as update the post once a month with who contributed.