A website as big as this must have some expenses, though I doubt that they are a terrible burden, I know a way to earn just enough money to keep a place like this going.
https://www.projectwonderful.com/I use this service for my own website. It doesn't bring in very much money, but I've found that it almost completely covers my own website's expenses, ans leaves only a little left coming out of my own pocket.
Yes, it is ads. You'd be selling adspace on the website. The great thing about this though is that you get control over what ads appear. You get to set controls on what rating of ad/website you want to advertise, and if you find some inappropriate or scam artist website trying to advertise, you have the power to ban the user from ever advertising on here again. In other words, you get control over who's advertising.
The money, though very small, admittingly, is constant. People bid for the adspace, and they pay for the amount of time their ad is visible on your website, not if anyone clicks on their ad. I get a few cents a day, but since this is a higher-traffic website than my own, I imagine that you'll get higher bids.
You can use this money to pay for bandwidth or software and the domain name registration, take the burden off of whomever pays for all this. Just a thought.