Even though these links are against the rules, I just wanted to comment on my experiences...
Neobux seems to have become worthless after they switched their guaranteed ads from a penny to a tenth of a cent yet kept the cashout thresholds the same. After being with them and having cashed out a few times, when they made the switch, my next cashout was at $8 which would take forever on my own to reach. Additionally, I had a bunch of refs, but when they made the switch, all of my direct refs stopped clicking and my rented refs also tended to stop clicking as much too. To further aggravate issues, all of the referral rental prices remained the same so with less income, I was not able to renew the rented refs I did have and eventually all of my refs disappeared. After that point, I no longer went on to Neobux, and I have lost all of the respect I had for them.
ClixSense on the other hand is much better. They too started posting ads for less than a penny per click, but at least their guaranteed ads stayed at a penny per click. Also, the cost to upgrade your account is very low compared with other sites, and (at the time) they gave a bunch of ads (500+) as soon as you upgraded making it much easier to cashout. Finally, ClixSense has a toolbar that alerts you when there is a new ad that you can click on; this way I can log into FC, write a bunch of stuff in the forums, and still be alerted when a new ad is available so I just switch tabs and click on those ads.
Both are PTC sites, tho, so you won't get rich by being a part of either one, unless you are good at getting referrals. Also you tend to see the same ads over and over, so it does get boring. At least with FC, the forums are always interesting!