Why you should care:
If these bills were to pass they will either radically alter or shut down sites like Twitter, Youtube, Flickr, and 4chan. The government can order service providers to block websites for infringing links posted by any users.
Risk of Jail for Ordinary Users
It becomes a felony with a potential 5 year sentence to stream a copyrighted work that would cost more than $2,500 to license, even if you are a totally noncommercial user, e.g. singing a pop song on Facebook.
Chaos on the Internet
Thousands of sites that are legal under the DMCA would face new legal threats. People trying to keep the internet more secure wouldn't be able to rely on the integrity of the DNS system.
How you can help:
There is a petition site that you could sign called American Censorship. Not much else to do but to hope this doesn't pass!