Well, I spent the afternoon calling registered voters in swing states from my cell phone in central park. I got set up by these guys:
http://www.democracyinthepark.org/
If you're interested in helping, it's a nice way to spend a couple hours out in the sun while helping defeat Bush at the same time. Although we were warned at the outset that we might not reach that many people, I reached a good three or four people per sheet of phone numbers, and got their information as to voting preference, etc.
I have to tell you something: It's very frustrating to speak with a voter who's undecided, but when pushed, says she's leaning towards Bush because her "son is on a aircraft carrier" and she thinks as long as we started the war, we should "see it through." (As if Kerry wouldn't see it through). Despite your instincts, you're not supposed to argue with them, just take their information so that voters can be targeted for GOTV when the time comes.
Anyway, the guys who run this organization are a good group of people, working hard for the upcoming elections. If you have a free weekend day, I would definitely grab a friend and go help GOTV:
http://www.democracyinthepark.org/