I hardly go on Facebook anymore mostly because of all the advertisements that get interleaved into the news stream. It's definitely a case of, if you don't like it then don't use it. There is no one forcing you to use Facebook and if they have a user base that is willing to put up with an Ad supported experience then so be it. AdBlock helps a lot in keeping at least the right hand ads to a minimum. It's funny going on a friends computer who doesn't have AdBlock and being surprised at the amount of advertising on Facebook. As an aside, I love my Nest thermostat.
The developer toolbar mostly. I do a good amount of web dev so its helpful. Taking pdf screenshots with a single command has come in handy. Also the 3D view is gimmicky but pretty awesome. Tab groups is another favorite.
There still seems to be some sort of memory leakage though. I have to shut down the browser every so often to clear out the 3GB of ram it suddenly decided it needed to have.
Interesting idea. Instead of simply saying people can't post if their karma is too low you could take the users total Karma relative to 0 and add a sorting feature filter that sorts based that. Only problem is new people would get buried pretty quickly and it may feel like they are trying to get someone's attention from across the room while in the middle of a pack of screaming monkeys. Adding a sort by "new" feature could help new users get their voice heard and voted up or down accordingly. Just a thought.