The ads are optional - you can block them if you want. Other options for ads that are, in fact, paying decently, are low risk as far as getting drive-by downloads and other malicious things, and can be relied on paying regularly and promptly are few and far between. In addition, most ad sites don't have the option of displaying links only, and on a forum I do not want rich media clogging up page loading.
If you value privacy above all else, then any alternative ad provider will be blocked by you too, as they are, by definition, always third-party content.
Alternatives for donations are, unfortunately, also limited.
Most alternative e-payment sites require you to be a registered charity to be allowed to accept payments. Asking for gifts otherwise is apprently a faux pas in today's economy (I don't understand why. If people want to give money in thanks, let them?)
Google Checkout is, as far as I know, for selling only, not for donations. Same with Amazon.
Having the ads as they are now has little impact on the forum, isn't too intrusive, and I think a good compromise for paying a small part of the electricity bill for my little in-house server.
If you know of viable alternatives, keeping the above in mind, then please let me know.