What some of the ISPs would like to do is to be able to overtly practice traffic shaping. Certain types of traffic, and traffic from certain sites, would receive higher allocations and priority than others.
YouTube/Streaming video is one example. Streaming video is bandwidth intensive, and utilizes a lot of resources. Many ISPs also have a piece of the cable TV market. Certain ISPs have argued that because streaming video places "undue" demand on their infrastructure, they should be able to shape the traffic (specifically, put a big tourniquet on the pipe to slow the flow of data), so that users of streaming video don't "Adversely affect the quality of the experience for the internet user community at large." Alternatively, they'd like to be able to charge a premium to the sites that offer up these services (like YouTube, Hulu, etc.) to cover the increased cost to infrastructure.
And it's all a load of codswallop. It's a cash grab, on one level, and a way of protecting their vested interests in old school cable TV.
My personal opinion of this: I pay good $$ for the highest residential bandwidth available in my area. Gimme my bandwidth. It's not up to my ISP to determine when and how I get that bandwidth.
There are other technologies that are severely threatened by network shaping and a lack of neutrality on the net.
Online multi-player gaming is often used as another example of an activity that is bandwidth/resource intensive.
And again, my attitude is, I pay for the bandwidth, so give it to me.
BitTorrent is a favorite case used by the ISPs, who can easily detect the types of traffic associated with Torrents, even if they can't really see the content of the traffic (thanks to encryption in most current Torrent clients). The ISPs argue that this is a huge drain on resources (and, granted, it is), and also that it primarily supports piracy.
A) I'm not going to make the argument that most torrent traffic is legit. It isn't. Most torrent traffic is associated with piracy.
B) It doesn't matter. Because of encryption, the ISPs are unable to determine what's within the torrent traffic. They can only detect that certain traffic patterns are associated with torrents. And not all torrents are about piracy. Torrents also happen to be a fantastically economical way for the FOSS community to distribute ISOs, and large software packages. For an independent publisher who doesn't charge directly for their software, this distribution model can make the difference between profit/bankruptcy. Paying for dedicated hosting to distribute software packages can be freaking expensive (as I'm sure most people here are aware of), and it can be difficult to manage spikes in demand. Torrenting your software avoids these limitations, both technical and financial.
And having lots of independent developers out there coming up with creative, innovative applications can do nothing but good for the industry as a whole.
Net neutrality matters, on a great many levels. This is one case where the government should get involved, and set up massive punitary fines for ISPs that try and shape traffic. Private companies with the legal ability to shape traffic will use it, and they will use it to their own monetary advantage, not to the benefit of the end user.
Relying on the market to sort the issue out is foolish. It is incredibly difficult for the end user to determine when this is happening. At the same time, the ISPs have a large incentive to engage in the practice and try to cover their tracks.