The US political system is broken. Everyone agrees on that. For an explanation, see This American Life's recent episode on campaign finance. Politicians must fund their campaigns by asking lobbyists for money. In return, lobbyists ask politicians for face time to explain their corporation's interests. Not some politicians; all politicians. Unless there's a public outcry, the interests of the citizens are outweighed by the interests of the paying corporations.
The most idealistic among us think that we can change this with grassroots activism. They believe that the internet will allow the people of the US to band together and make our politicians accountable again.
I don't buy this argument. People simply don't have time to care about most of the issues that affect them. Activism is a full-time job. That's why we have a representative democracy. We elect politicians to represent our interests in the lawmaking process.
Thus, I propose a "new" form of activism effective in today's political environment: corporate activism. Instead of trying to convince people to donate their time and money to a cause, construct a business whose interests align with your cause.
If your goal were to reform copyright law, you could create a business that would benefit from shorter term of copyright. For example, Netflix for public domain movies. If you want to eliminate software patents, build a software company which doesn't create or buy any patents. Your company would be certain to infringe on thousands of software patents, so it would be incentivized to lobby for patent reform.
The difficulty in creating your own activist corporation lies in keeping the company's interests aligned with your cause. Netflix could have been an advocate for sane copyright law, but now its deals with content companies form a barrier to entry which protects its business. Netflix would face increased competition were the US term of copyright to shorten or the penalties of copyright infringement to lessen, so it has no incentive to advocate copyright reform. Likewise Google could have been an advocate for net neutrality, but it struck a deal with Verizon, an opponent of net neutrality, to convince Verizon to carry Android phones.
Despite the risks, I see corporate activism as the most effective way to change the US political system today. This isn't how it should work, but campaign finance has been fixed, there are no reasonable alternatives.