The website already earns enough. Donations wouldn't make a big difference, so I don't feel comfortable directly asking for them. Nonetheless, I'll give it a try. Thank you for the suggestion!
Also, while we're on the subject: I would love it, if free software came with a token product. For example: a "star" tier that shows up in your online profile, or something. This way, people can donate and make it into a business expense.