I think Flattr has (or had) a model like...
1. you give Flattr a constant $X per month (you choose the X)
2. Flattr tracks the content you consume, using a browser plugin
3. Flattr divides up your $X among the creators you viewed, and sends it to them
I never used it, but it seems like an interesting model. I like the idea of spending a flat $30/month on "internet content", without agonizing about whether X webcomic deserves my Patreon support.