The first thing I recommend to Americans is to sign up for the ACT! for America email alerts. They give you lots of opportunities to write letters, call, and apply pressure to politicians for anti-Sharia legislation. And they give you good articles to share with your friends and family. Many other countries have similar organizations, like the Q Society in Australia and ACT! for Canada.
Another good thing you can do with your computer is visit web sites or popular blogs or Facebook pages where the "Islam issue" is being discussed, and make persuasive arguments with courtesy and class, give good information, and provide links to more information. I'm not talking about counterjihad sites. I mean anywhere you find Islam being discussed where you could add to the discussion with some real information. You might even sign up for Google News Alerts with the search terms, "counterjihad" or "Islam means peace," and then jump into those conversations.
Another good way to inform people is to go to Yahoo Answers and watch for questions to come up that you can answer with good information about Islam, and make really good answers.
And also adding information to Wikipedia or even writing pages for Wikipedia.
Yahoo Answers and Wikipedia are often the first results on a Google or Bing search, so if you can get something there to answer questions when someone is searching, that's a great place to reach people. The result will be seen and you're providing the information at the perfect time: When someone wants to know.
The place where you will have the most impact is reaching people who are arguing in favor of Islam, or at least against counterjihadists. What we're trying to do (and where our impact will be greatest) is reaching those who don't already know that Islam is not a religion of peace.
It's tough work because sometimes people are hard to reach, but many times people have told me that they were at one time against counterjihadists and thought they had it all wrong but eventually something got through to them and they started investigating it for themselves, and that's the beginning. As soon as someone really starts looking into Islam, they will become counterjihadists, because the facts speak for themselves. Our job is to make the "undecideds" curious enough to see for themselves. This is best done in person. But a close second is what you can do online.