So political solutions are great and all if we can get them implemented. Hopefully that happens in Seattle, but for a lot of Americans, it's not going to be viable. So how do you protect yourself from Comcast, Verizon et al. stealing your browsing habits?

1) Install HTTPS Everywhere. While Comcast will still be able to figure out the sites you visit (and thus can glean quite a bit about you from that), they won't be able to see the exact information being sent back and forth between your computer and the server. It is therefore only a partial solution.

This is incredibly easy, not at all disruptive, and everyone should do it now.

2) Consider using a VPN or Tor. With either, Comcast only knows that you're using it. They can't track your browsing habits at all. The downside with VPNs? They generally charge a fee to use. Also, the VPN service itself could be tracking and selling your browsing habits. Tor offers even better privacy, but the cost is speed; Tor is slow. Also, your browsing experience may sometimes seem a little wonky because you don't know what country you'll appear to be browsing from so you end up breaking some localization. The Tor Browser is available here.

With these options there are tradeoffs, making them not for everyone.

Be aware that you may have other services running (e.g. a dedicated email client or gaming platforms like Steam) that won't necessarily be hidden.

3) Probably the best organization you can donate to is the EFF. Not only do they do lobbying and advocacy, they also do court challenges and consumer education. They create open-source tools that make protecting your privacy much easier. In short, they cover all the bases. They're a non-profit that uses its contributions wisely.

Further information on securing yourself here.
Information of interest especially for activists and protestors here.