Just spitballing here since I'm wasting time at work... I think it would make it cool if you vote on a post's interest to you using a continuum rather than a binary.

Let's take reddit (or snapzu, for that matter). Interest is either -1 (a downvote), or +1 (an upvote). if you don't touch it, then your score is 0. Sorta binary, I guess. Trinary?

A continuum vote would be more like... ok. picture a line the width of the post. Hard left is green, hard right is red. Middle is yellow. Grab a slider and move it left to right, depending on how much you give a shit. By default, it stays in the middle (yellow). Sort of (lightly) colors the background of the post. At the end of the day, you get a bunch of yellows, some nice teals, perhaps some greens. Oh, and 2-3 reds since those were boring.

Add a little intelligence in so that after a while, it begins to auto-color new posts for you (perhaps a square beside the title?). See several new red posts you know you're probably not gonna be interested in it. A light green comes through and you're hopping in to vent your spleen about the topic of interest. You might hit up some yellows if there's enough comments.

So, there you go. a color-coded voting system with three states depending on interest. Based on "color interest" instead of hard numbers.

But, I suppose colors are hard to tally up at the end of the day to see what your karma score is...

Spoiler - it won't be an actual thumbs down button. From the Atlantic article above:

Zuckerberg added that the “Dislike” button wouldn’t work like Reddit’s up- and downvote mechanism, which is probably the most famous “dislike” button on the Internet. Instead, he said, users would now have a technical way to express regret or sympathy in a situation.