In the past, I have been a participant in class action suits that were the result of my using a product or service. I was notified by mail of these. But some are targeted to a wide audience and you find out about them from the news, friends or the internet. I always like to notify friends of the ones I think may interest them, and I'd like to share how I find them.
News of class action suits can be found in conventional newspapers. My daughter told me about the article she had read and by acting quickly, I received a free high-end mascara just by signing my name and standing in line about 10 minutes. However, you have to move fast. Two days after I received mine, I took my daughter-in-law to get one and they were out - and we tried two stores.
To find current class action suits, I use this site. They list current and open class action suits. Their web site is www.topclassactions.com(also listed in resources). It's easy enough to check it out every day or week.
I love www.smartmoney.com and "deal of the day". The one I read about today is the Bank of America overdraft fees/charges class action suit.
Another site that I found is www.consumerist.com (http://consumerist.com/tag/class-action-lawsuits/. They don't have a list but report on current suits. As of this writing, they list Sprint and early termination fees.
Be sure you are entitled to be a part of the class action suit.