I see a lot of projects closing down due to lack of time/funds. Why don't more projects take sponsors and display a banner on their readme page.<p>For example Vue.js generates 10k/mo with sponsors: https://github.com/vuejs/vue
Specific sponsorship ie a company sponsoring a project and having mention/logo/link on a readme/sponsors page etc I think is quite acceptable.<p>A random Google ad (particularly with the privacy invasive tracking that goes with it) on the page is going to give an altogether different appearance, particularly if the project is using free resources such as GitHub/read the docs/etc.
It's not a classical open-source project, but what we did with our React.JS koans (and other our OSS repos) was to advertise our React.js book in the README and give a discount code. Essentially, it's an ad for our own book.<p><a href="https://github.com/arkency/reactjs_koans" rel="nofollow">https://github.com/arkency/reactjs_koans</a><p>Thanks to this solution we've had more money to work on this and other OSS projects.