Put up an ad for a better modem. Or maybe some Amazon affiliate link.
Or compile all the info into an ebook/pdf and put a "support this site and get all the info in a printer-friendly pdf" link to some self-publishing platform. I think they usually handle payments for you.
There was a project featured on HN just yesterday that allows you to sell documents stright from Dropbox/Drive[1]. Although they seem to be just using PayPal.
There's also Flattr[2] for small donations to websites. But they're probably more popular in Europe.