I've thought about how this relates to Stumbleupon as well. I never used it myself, but it came up while I was looking for things similar to Findka.

I'm actually just starting to implement features like these. If you make an account then go the the Account tab, you can enable a public profile like this[1]. So far I'm planning to add follow/subscribe, commentary (i.e. comment on items instead of just rating them), and showing users who've rated the same items as you.

[1] https://findka.com/u/f962c926-43e1-406d-825d-3d7a4880befa/