If Net Neutrality is NOT passed, it is almost certain that you will have to pay extra money to the providers of the internet (the folks who own the cables and lines) to get access to many sites. The only sites that will be free will be corporate sites who are willing to pay tons of money so consumers will have unrestricted access. Small businesses, blogs, fansites, private websites... all will load much slower... if they load at all.
The threat is real. It's ALREADY HAPPENING. Call your congresscritters and let them know that you think the internet should be protected from corporate greed.