That might be tricky because you'd have to determine how much "one tip" (/click,submit) is. Even if a small amount was decided upon, I wonder if there would be too much added stress along the lines of "is reading this worth the X of a tip?" Which, also, is hard to know until you've actually consumed the whole item, at which point a lot of people have probably linked somewhere else, flowing their way across the web.

I think that this might be helped if it acted like playlists, or bookmarks, where clicking the button would add the site to a list. Later you can opt to donate to items on the list (or provide a single donation split evenly among everything on the list).

Of course, I doubt many would actually use such a feature either.