I would only suggest writing for sites such as Suite101, the Examiner, and Associated Content in order to get a few publishing credits.  And maybe to place articles that won't find homes in normal print magazines.  For example, I'm a history buff, and while American History print magazines are fairly common, not a lot are interested in the different dynasties in ancient Egypt. 

I found a post by another blogger that lists sites that she trusts.  And some that she has written for.  Out of respect for her, I'm going to post the link to her post, NOT copy and paste her information. 

Now, I haven't tried all of the sites listed on her post.  As I've stated before, my online freelance stuff is limited to Suite101, the Examiner, and A.C.  But feel free to check out her sites. 
(And should you get paid, find the experience good- or bad- please let me know!  I'll post a review of the site- and a link to your site, if you wish.)

Popular Websites That Pay You to Write Articles: http://www.pookiestopmoneymakingwebsites.com/2010/05/popular-websites-that-pay-you-to-write.html#more

 As I told you earlier, I started writing for Suite101 about six months, but wanted to give it a fair chance before I gave it an official grade or recommended it to anyone.  Overall, I would recommend it to writers who are new at freelancing (even if you're not new to writing).  The experience, learning, and publishing credits make up for the fairly poor pay.   If you're interested in becoming a Suite101 writer, there is an application process. 
Please feel free to apply by clicking here: www.suite101.com/invite/676850.

Positives-
They have a great editorial staff and tutorials that will help you learn article writing basics.  Most places have the same requirements- a certain format for sources, not using "open" links, no first- or second- person writing, etc. 

It will get you some publishing credits.  Now that I have quite a few articles published there, it has been much easier to get other freelance writing jobs.  Ones that pay a lot more.

They have a great community and forums.  I've gotten leads on other jobs from the forums, not to mention a lot of great advice.  Unlike some writing forums out there, I don't think I've every seen a rude, snappish remark.  People are open, friendly, and willing to help each other. 

Negatives-
THE PAY.  I have to be honest.  I've written 40 articles over the last six months.  My income so far is a little over $21.  That means I only got paid about 50 cents per article.  Thus far. 
-----They only pay for page views.  No up-front article pay.  I really, really don't like this.  Even a $1.00 an article plus page view pay would have tripled what I've made so far.  Right now, I'm writing for other sites, and using Suite101 for my religious articles. 
-----However, I will continue to get revenue forever on those articles.  Plus I have reprint rights.  Suite101 only takes electronic rights for the first year. 
-----I write for a non "high-paying" area.  Finance links usually garner about $10.00 per click.  But I'm not a financial expert (IRA's, tax laws, etc.).  I write about religion for Suite101.