If you're a Republican, you might want to skip this post...or be inspired by it to get to work for future elections. For the rest of you:
Presumably, the bill is going to pass by one or two votes in the House today. I'd like to be able to say that if one fewer Democrat had been elected, the bill would fail, but that's probably not true. Still, it was certainly true that had one fewer Democrat been elected to the Senate, the bill would have failed or would have been substantially different, and you never know in the House; maybe if the Democratic caucus was one smaller, they couldn't have done this. If not one, then maybe two, or three, or half a dozen; at some point, even Nancy Pelosi couldn't have found enough votes, even with a nominal majority.
So if you worked on, volunteered for, or gave money to one of the campaigns that made a different, well, not only should you be happy about the bill passing today, but you should step back and be proud of what you -- not just Pelosi, or Barack Obama, or Harry Reid -- but you accomplished. If you worked for Betsy Markey, who won by 41,000 votes, or Jim Himes, who won by 12,000 votes, or Mark Schauer, who won by 7500 votes...well you and the others who put these candidates over the top are responsible for today's margin of victory. Or, of course, if you worked for Al Franken, or any of the other Senators who squeaked by in 2008 (or 2006 or 2004). I don't know that things would be different had Hillary Clinton been president, but perhaps, and so if you worked for Obama in the primaries, this is you, too -- and the general election margin wasn't small, but had he won fewer states, perhaps this doesn't happen.
And then there are all those who made phone calls or sent emails for OFA or on their own. The anti-reform forces have been far more visible over the last year, and there's no way to measure the effects of this kind of stuff, but it's probably reasonable to say that if Members of Congress had heard only from one side, it would have been harder for them to support the bill.
Back to all that door-to-door campaigning. I've referred to this before, but be sure, if you worked hard for a Democrat in 2008, to read this Seth Masket post about his research that found that electioneering really did make a difference.
Look, one of the things that makes politics hard for rank-and-file voters in the United States is just how impossibly large this nation is. In a country of 300 millions, no matter what you do, it's often going to feel like it's a meaningless drop in the ocean. And given the legislative process, time passes between campaigning and enacting bills into law, and by many people have moved on to other parts of their lives. But individuals, and especially small groups of people, really can make a difference. This battle over health care reform is one time when it wasn't just the lobbyists, or the interest groups, or the politicians...whole bunches of small groups of people, in states and Congressional districts across the nation, turned a handful of Senate races and a dozen or two House races around and, sixteen or so months later, their work is, today, most likely going to change the country. If you're one of them, it's a day to be proud of what you've done.