When it comes to activism, the past decade or so has been focused primarily on email. Remember when you would receive those petitions directly in your mailbox and you would simply add your signature and email it to the next person, trusting that eventually the last person—or the petition’s creator—would somehow turn it in to the proper people of power at the end and it would make a difference?

Then nonprofit companies began distributing email campaigns to get activists to visit their webpages and take action, either through a adding their name to a petition or a pre-written letter to an elected official. While some of these offer faxes to be sent from their offices, most simply offer a free email sent to your member of Congress or another appropriate leader regarding whatever campaign it is.

These campaigns are still effective to some point; I for one still sign almost every one that comes to my inbox (as long as I agree with it), and I get a few dozen of these each week. But many people are more focused on social networks today, which is why it’s important to utilize them for your cause. In fact, when I see a charity website without links to a Facebook fan page, say, or a Twitter account, I sigh and think, hopefully they’ll stay afloat. Nonprofits are taking a pretty hard hit right now due to the recession and not using these free and simple tools could cost them a lot of supporters.

While there are plenty of social networks out there to use for your cause, I find that the four most important ones are the following:

Facebook. Facebook is already set up to feature your causes through highlighting them on your profile. You can raise money, show what you support with badges, sign petitions, and join your cause’s fan page or group to stay in the loop about important actions and events. If you have a cause, creating a Facebook page for it is a must.

YouTube. Videos are popular as long as they are short and sweet—meaningful yet interesting, and the funnier or more moving, the better.

Twitter. Twitter is quickly becoming the most popular site on the web. Given that people are bombarded with information all day, reducing your message to just 160 characters and sticking a link to your action is likely going to be more effective than penning out a long, heartfelt email.

MySpace. If you’re attempting to reach a younger crowd or to simply get visibility, MySpace is your place. You may not get as much active participants as you will at Facebook, but you’ll likely get more “friends” for your organization and possibly a larger audience.

Do you use your social networking profile for your cause? Have you ever created an account just for, say, leukemia or animal rights? Share your experiences below.