(I posted a very similar diary four years ago. I have a hunch it might be useful tonight, so I've updated it.)
Those of us fortunate enough to be active in the netroots during the 2004 and 2008 Presidential elections recall that one of the notable successes of online Democratic activism was our response to the debates. Those years, the liberal netroots owned the post-game online action. In emails and online polls, there was no doubt the netroots had become a force to be reckoned with.
What to do tonight
Polls
Keep a lookout for online debate reaction polls. For most of them, you'll be able to vote only once (unlike that legendary PBS poll from 2008 with more votes than people on earth). For some polls, however, repeat voting will be possible.
When we discover a poll, post it either in an open/debate thread or (if you have a bunch of info) obviously, post it in a diary. Note, however, that many polls will be found quickly, so look before you post.
Automated voting
If we find a poll that allows for repeat voting (unlikely these days, but who knows?), Firefox is all the equipment you need to make it happen. In order to do this, you may need to disable cookies in the browser. Vote in the poll, and on the results page, right-click and select "Reload Every >" In the sub-menu, choose "custom", and in the dialog box that then appears, choose 0 minutes, 1 second. Firefox will then reload the page, and you'll be asked whether you want to re-send data on the reload. Choose "yes", and you'll then have Firefox set up to vote once per second.
Interestingly, you can do this in multiple tabs to vote more than once per second.
Facebook and Twitter
Spread the word! Thinkprogress and Talking Points Memo will be out quickly with debate factchecks; share and like them liberally...
Emails
Both for letters to the editor and for directly influencing pundits/shows after the debate, a blast of postgame emails will help to shape media opinion of how the public felt about the debate. The best list I've found is here -- if anyone has more, please post it in comments.
Conclusions
Post-debate can be fun, and we have a real chance to influence perceptions. We have numbers and organization the Right still can't match, and this is one of our best opportunities to use it.
The post-game of the VP debate last week was a major illustration why active response is so necessary -- polls of undecideds found that Biden won the debate handily, but the media ran with the right wing spin (Biden smiled! the horror!). We can make the difference in the outcome.
Tonight, when the right wing tries to make "Obama was too aggressive and mean!" the story, our response will be key in telling a different narrative.