Though it's been around for a long time, a recent popularity boost seems to have been administered to the "Karma" system - instead of ratings on things, a thumbs up/down system often not only on the primary content of a website, but also on its comments. And it's a load of crap. Why is this?
If you've been on YouTube at any point within the last several months you can probably answer that yourself. Karma clearly means very, very little, yet as a result of these arbitrary numbers and thumbs, videos get inundated with junk comments. The most annoying by far is the one from people that seem to need karma to be happy with themselves - "Thumbs up if _______". Since the Game Maker Community got a Karma (well, a +1) system, numerous people's signatures contain a little or large arrow trying to steer people to clicking it. Furthermore, you can tell there are people that are just commenting for the Karma, even though they don't mention it.
Another YouTube commonplace annoyance is "[number of people that dislike a video] people are [something bad mentioned in the video". This isn't just trying to vacuum thumbs ups, it's also a prime example of the internet trying and failing to be funny. Sure, it may have been mildly amusing at first, but on popular videos 20% of all posted comments could be people with their repetitive quips.
The ability to "thumbs down" just attracts attacks too. Take any video by the likes of John and Edward Grimes ("Jedward") or Justin Bieber. Though I can't hate Jedward - I find them far too hilarious - Bieber's music makes me want to go deaf (not that I hate him as a person, I'm sure he's a friendly little girly-voiced boy and if I could be in his position I'd be singing songs about how I'm considerably richer than you!). But because I don't like Justin Bieber, I don't watch his videos. As a result of this, I don't thumbs down his videos. The vast majority of people would be in the same situation - not rating down his stuff purely because what's the point? Yet, thanks to the "net-minded" - people that find it hilarious to try and ruin a successful 16 year old kid's life - the thumbs downs match or even beat the ups.
And it does genuinely steer what you say. The dicks will try to collect thumbs downs by going around dissing everything everyone else likes. The people worried about their reputation to any extent will change their opinions so people don't go against them. The sheep will just reiterate what other popular people say to get those same thumbs from them.
It just all seems so stupid to me. You're welcome to comment on this with your opinions on Karma systems, but keep your thumbs to yourselves.