It's literally the absolute least you could do.
This is what I'm worried about. Who really stopped SOPA? You can bet that anyone who signs up for this will go around touting how they stopped SOPA, just like the guy next to me pretty much single handedly saved Haiti in 2010 with his $5 donation to the Red Cross.
There is a disparity between giving money so that others can continue to do work and being the one doing the work. I want that distinction clear, and to remain clear. The doctor who flew down to Haiti to personally help is infinitely more valuable than someone who donated.
EDIT: I'm not saying that this is useless or dumb. It's a step in the right direction, albeit (IMO) a small one. I just don't want to see "I signed up- I'm going to save the internet!" I think the people who really devote themselves to these causes should be respected on a different level than those that, for instance, sign up for this.
People who aggravated against SOPA certainly did something -- an important thing -- but people who made hard decisions, called or emailed their representatives and really coordinated this effort did more.
Really? Let's say I donate enough money that the Red Cross can afford to send an additional doctor to Haiti. How is that not in the same ballpark as volunteering your time as a doctor to go work there?
We should care about the effects of our actions, and donating money to effective charities (see http://givewell.org) is one of the ways we can have the biggest positive effect.
(I take this seriously; I give about 1/3 of what I earn as a programmer to the most effective charities I can find.)
Going back to the Red Cross example: If I'm a doctor in the US I'm making very good money, I get to see my family every day, and I have a very high standard of living.
It takes one of those doctors (not necessarily from the US, but I imagine most doctors live well) to give all of that up and fly over to a country in ruins to help. Without the people who are willing to really make those sacrifices, we've got a bunch of money and that's it. Money in and of itself is not what is usually needed to rectify situations.