You're probably not going to get rich writing for a living, but here are two places I've written for. I've actually been able to pay a few bills with money I've earned from these two sources. If you have a similar goal as mine of becoming your own boss and deriving income from many sources, these are great ways to do so. I am, in no way, affiliated with these sites or am I earning referral bonuses by recommending them to you.
You'll be commissioned to write ad copy, reviews, articles, blurbs, etc. You submit a first piece and you are given a star rating anywhere from 1 to 5. The original rating dictates how much you make per word. Supposedly, you can increase or decrease your star rating after you write several pieces. Be forewarned, the average is a penny a word. Still, it's better than nothing per word.
There is a database of available work, or "orders," organized by the client's requested topic area and star rating. You can write for any level below yours. For example, if you have a 5-star rating, you can write for all star levels. If you have a 3-star level, you can write 2-star and 1-star articles. There are also chances to earn more than your star rating dictates if you are willing and able to write about very specific topics as part of a "team order." You must apply for these positions and they often take a lot of research and/or inside knowledge. The highest price I've seen listed is 7¢/word and that's extremely rare. The average is still 1¢-2¢.
Pros: You can get some experience in copy writing. You can work whenever you want. It's possible you can be given direct orders, meant specifically for you.
Cons: Low pay and availability. If you're a 3-star writer or below, there might not be much commissioned work for you. Most writers are rated 2-star or 3-star. Plus, with higher star writers being able to write at those levels as well, you're really scratching and biting for work.
You can submit articles or creative pieces about almost any topic and you're eligible for a daily prize. There's Gold - $50, Silver - $30, Bronze - $20 and Photo of the Day - $10. There is no voting system (though they temporarily had an Author Prize of $10 based on votes on top of the regular prizes). How often you win really depends on how well you write. Having a lot of views, shares, "likes," and comments only affects your chances of winning nominally. All articles are judged by the editors who also award the prizes. Not to toot my own horn but, I win fairly consistently and I usually submit once or twice a week. I've won all of the available prizes at least once (not including the author prize). Last I heard, they are considering setting up a similar system to textbroker.com in addition to the daily prizes, but so far, it has not been enacted.
Pros: You can write about virtually anything that you want. You can submit whenever you want. You can win up to $50/article. You have the chance to win every day you submit something. You can use it to drive traffic to your blog, twitter, youtube, etc. There is no exclusivity policy.
Cons: It takes up to a week for your articles to be approved unless they are genuinely time-sensitive pieces. There is no way to predict how much you'll earn because you never know if you're going to win. You may never win.
Good luck and happy writing!