Most of these are very easy to earn with, simply click an advertisement and view it for a predetermined length of time to earn a large amount of bitcoin! There are also a few here on which you can watch youtube videos and earn bitcoin.
Click2Dad- One of the highest PTC earners on this list, you can easily make 0.1mBTC in a day.
BitToClick- Here you can click ads, do offers, complete tasks, advertise your website if you have one, and they even have a forum. A big potential earner if you want to complete tasks.
route66traffic- A traffic exchange where you can direct traffic to your websit, AND earn bitcoin by clicking ads.
CoinTasker- Here you can watch videos and complete tasks for bitcoin. A HUGE earner, you even get 0.0005BTC just for signing up, and 0.00001BTC for logging in each day.
BTCClicks- Simply click an ad, view it for a length of time, and get free BTC!!! A very nice earner if you choose to purchase a membership with your earnings, also comes with a free advertisement!!
CoinAd- One of my favorites! An EXTREMELY fast earner at about 0.0003BTC every day or two!
ABitBack- A pretty good earner, you can watch videos, take surveys, complete offers, and even listen to their radio to earn points which you can cash out for bitcoin, litecoin, or cash!!
Tremor Games- Another favorite of mine!! You can watch videos, complete tasks and offers, and even play flash games to earn bitcoin!! Probably one of the highest earners out there, you can manage to get around 0.002BTC a day if you work at it.
CoinWorker- Complete simple tasks and earn bitcoin, very simple, but takes a while to get a payout, which will be very high when you do get it.
Bitvisitor- Simply enter your wallet, stay on each page for 5 minutes, and click next to get your bitcoin! Pays a decent amount, usually anywhere between 0.000008BTC to 0.000070 per page, you MUST click the next button in order to get your bitcoin, however.
earnfreebitcoins- This website works pretty much exactly the same as bitvisitor, only you don't have to view some pages quite as long.
BitcoinClix- Another website similar to bitvisitor, but with a much higher payout threshold.
BitcoinGet- Get paid to complete simple tasks, watch videos, or complete offers. Payouts can be very high if you complete the right tasks or offers!
________________________________REAL MONEY SITES_______________________________
ClixSense-My personal favorite for earning real money. The most i've earned in one day is $5 US, by playing the clixgrid game, which is the very reason why I like this one so much.
NeoBux- Works pretty much the same as ClixSense.